FormalPara Key Summary Points

Why carry out this study?

Vaccines that protect against invasive meningococcal disease (IMD) are key to achieving the global goal to defeat meningitis by 2030, but they are not routinely administered in Colombia.

This study aimed to describe the recent epidemiology of IMD in Colombia.

What was learned from the study?

The incidence of IMD in Colombia was approximately 0.1–0.2 cases per 100,000 population, and IMD lethality was approximately 20%.

IMD cases tended to be more common in densely populated areas and poorer neighborhoods.

Recent IMD cases were mainly caused by serogroup C, followed by B and Y, hence vaccination against these serogroups could be beneficial.

Digital Features

This article is published with digital features, including a graphical abstract, to facilitate understanding of the article. To view digital features for this article, go to https://doi.org/10.6084/m9.figshare.24297556.

Introduction

Meningitis is an uncommon but serious and potentially fatal infection that can be caused by bacteria (e.g., Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis) [1] or viruses (e.g., mumps virus, herpes viruses, and measles virus) [2]. Of these, N. meningitidis is of particular concern as it has the potential to cause large epidemics [1]. There are 12 N. meningitidis serogroups, of which six (A, B, C, X, Y, and W) can cause epidemics [1]. N. meningitidis can cause a range of invasive diseases, typically meningitis and/or septicemia, but also atypical presentations such as septic arthritis, bacteremic pneumonia, and abdominal presentations [3]. Collectively termed invasive meningococcal disease (IMD) [1], these are associated with high morbidity and mortality [4].

Antibiotics can be used to treat IMD, while meningococcal vaccines can help to prevent IMD [1]. These include meningococcal conjugate vaccines that protect against serogroups A, C, W, and Y (MenACWY) and recombinant protein vaccines that protect against serogroup B (MenB) [5]. Meningococcal vaccines are recommended for various age groups (mainly infants and adolescents) in different parts of the world [6]. Targeting adolescents, who are associated with high rates of meningococcal carriage and transmission, can also help to protect other age groups [7, 8]. The meningococcal vaccines included in the national immunization programs in Latin America are as follows: MenACWY vaccine at ages 3, 5, and 15 months and 11 years in Argentina [9], MenB vaccine at age 2–4 months and MenACWY vaccine at age 12 months in Chile [10], meningococcal serogroups B and C (MenBC) vaccine at ages 3 and 5 months in Cuba [6], and meningococcal serogroup C (MenC) vaccine at ages 3, 5, and 12 months in Brazil [6], but there are no routine meningococcal vaccination recommendations in the other Latin American countries [6]. In Colombia, MenACWY vaccine is currently only recommended for outbreak control [11, 12], but has also been available privately for people aged 2 months to 55 years since 2015.

A previous study has described the epidemiology of IMD in Colombia during 2005–2011 [13]. The objectives of the current study were to: (1) describe the recent epidemiology of IMD in Colombia by year, age, serogroup, and region; and (2) describe and compare IMD cases and outcomes in different socioeconomic (SE) status neighborhoods in one Colombian city (Cartagena). This information will be important for authorities and decision-makers to consider when deciding whether to include meningococcal vaccines in Colombia’s National Immunization Program. It may also be valuable to assess the impact of vaccination [8], and for healthcare providers and their patients.

Methods

This retrospective surveillance database analysis examined all available data on IMD in Colombia in people of all ages. Data were mainly extracted from publicly available reports from Colombia’s Instituto Nacional de Salud (INS; National Institute of Health) or were requested under the Public Data Transparency Law from INS’s Laboratorio de Microbiología (Microbiology Laboratory). A key source was INS’s annual Informe del Evento (event reports) [14,15,16,17,18,19,20], which provide information on bacterial meningitis and IMD that are collected through the national public health surveillance system. Another key source was INS’s N. meningitidis laboratory surveillance reports, which covered 1987–2018 [21] and 2010–2021 [22].

Endpoints were: (1) confirmed cases of bacterial meningitis (N. meningitidis, S. pneumoniae, and H. influenzae) for 2015–2017 and confirmed cases of bacterial meningitis and other IMD for 2018–2021 from annual INS event reports [14,15,16,17,18,19,20]; (2) incidences of IMD (from event reports [14,15,16,17,18,19,20, 23,24,25,26,27] and laboratory surveillance [22]); (3) IMD cases and incidences by age group from laboratory surveillance [22]; (4) IMD deaths and mortality incidence (per 100,000 population) (requested from INS through the Data Transparency Law 2022–2029) and IMD lethality (i.e., percent of cases resulting in death) from event reports [14,15,16,17,18,19,20]; (5) IMD cases by serogroup from laboratory surveillance [21, 22]; (6) IMD cases by serogroup and age (requested from INS; PQRSD 2021–3166, 2022–1518, and 2022–2178); (7) IMD cases and incidence by department (region) from laboratory surveillance [22]; and (8) IMD cases and deaths by SE status neighborhood in the city of Cartagena (in Bolívar) (source detailed below). Incidences were calculated using Colombia’s Departamento Administrativo Nacional de Estadística (DANE; National Administrative Department of Statistics) population data [28].

For the SE analysis, data were extracted retrospectively from WCR’s clinical database, which was populated with data received by WCR from six hospitals (one pediatric and five pediatric/adult) in Cartagena, Bolívar. These hospitals notified WCR when they had a suspected or confirmed IMD case during ongoing outbreaks throughout 2012–2017. WCR and his team followed up on the diagnosis, clinical progression, management, and prognosis of all the reported cases and subsequently conducted serogrouping for all confirmed IMD isolates. For the present analysis, the identified IMD cases were stratified by neighborhood, for which we obtained the SE categories (low–low, low, medium–low, medium, medium–high, and high). Of note, hospitals in all SE neighborhoods were involved. People living in the three lowest strata (i.e., the poorest) receive subsidies for their domestic utilities, those in the medium strata do not, and those in the top two strata (i.e., richest) have to pay a premium for their domestic utilities [29, 30]. Hospitalization durations were compared between SE status neighborhoods using the Wilcoxon rank sum test with continuity correction.

Ethics committee approval was not required for this study as it was a retrospective secondary database analysis of publicly available anonymized data, either directly accessible or requested through the Law of Transparency, from the National Health Institute of Colombia [31]. Disclosure recommendations [32] were taken into consideration when analyzing and reporting the anonymized aggregated secondary database provided by Dr. Wilfrido Coronell from Cartagena. We obtained this information from the epidemiology service of each institution, from the surveillance system registry (SIVIGILA), and from the medical histories of the patients with the endorsement of each institution and the approval of the ethics committee at the Faculty of Medicine of the University of Cartagena.

Results

Bacterial Meningitis and Other IMD

During 2015–2017, there were between 269 and 509 confirmed cases of bacterial meningitis each year, while during 2018–2021, there were between 269 and 597 confirmed cases of bacterial meningitis or other IMD, resulting in a total of 3022 confirmed cases during 2015–2021 (Fig. 1 [14,15,16,17,18,19,20]). Overall, 37.1% of cases were due to S. pneumoniae, 19.6% to N. meningitidis, 8.5% to H. influenzae, and 34.8% were due to other agents (e.g., Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, and Listeria monocytogenes). In addition to the confirmed cases each year, there were also some cases that were designated as probable. For N. meningitidis, these amounted to 15, 14, 8, 9, 2, 2, and 0 each year during 2015–2021, respectively [14,15,16,17,18,19,20].

Fig. 1
figure 1

Cases of confirmed bacterial meningitis (2015–2017) and confirmed bacterial meningitis and other IMD (2018–2021) from event reports [14,15,16,17,18,19,20], by etiological agent and year. IMD invasive meningococcal disease

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IMD Cases and Incidences

Using data from the INS event reports [14,15,16,17,18,19,20, 23,24,25,26,27] and DANE population data [28], the incidence of IMD increased from 0.12–0.16 per 100,000 during 2010–2015 to 0.22–0.23 per 100,000 during 2016–2019, and then fell to 0.10 and 0.06 per 100,000 in 2020 and 2021, respectively (Fig. 2). The IMD incidence calculated from INS laboratory surveillance [22] and DANE population data [28] was consistently lower, but the difference appeared to improve over time, as shown in Fig. 2.

Fig. 2
figure 2

Incidences of IMD according to different sources by year: confirmed cases from event reports [14,15,16,17,18,19,20, 23,24,25,26,27] and laboratory surveillance [22];aConverted to incidences using DANE population data [28]. DANE Departamento Administrativo Nacional de Estadística, IMD invasive meningococcal disease

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During 2010–2021, the highest numbers of IMD cases were seen in the period 2016–2019, when there were 72–87 cases per year (Fig. 3a [22]). During the whole 12-year period, IMD cases most commonly occurred among people aged 15–29 years (143 cases), but, after accounting for population sizes by age [28], infants aged < 1 year had the greatest burden of IMD (0.52–1.47 cases per 100,000), followed by children aged 1–4 years (0.03–0.47 cases per 100,000) (Fig. 3b [22, 28]).

Fig. 3
figure 3

IMD a cases and b incidencesa from laboratory surveillance [22], by age and year. aConverted to incidences using DANE population data [28]. DANE Departamento Administrativo Nacional de Estadística, IMD invasive meningococcal disease

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IMD Mortality and Lethality

The numbers of deaths due to IMD ranged from 19 to 27 during 2015–2019, and then fell to 10 in 2020 and 4 in 2021 (Fig. 4a). Overall, most deaths occurred among people aged < 10 years [44 (34.6%)], 10–19 years [28 (22.0%)], and ≥ 60 years [19 (15.0%)]. However, the highest mortality by population size was among infants aged < 1 year (mean 0.30 per 100,000), although this varied considerably by year, from 0.00 to 0.65 per 100,000 (Fig. 4b). The second highest mortality was seen among children aged 1–4 years (mean 0.07 compared to 0.01–0.05 per 100,000 in the older age groups).

Fig. 4
figure 4

IMD a deathsa and b mortality (per 100,000 population),b by age and year. aData were obtained by request (PQRSD 2022–2029). bConverted to incidences using DANE population data [28]. DANE Departamento Administrativo Nacional de Estadística, IMD invasive meningococcal disease

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Regarding lethality, during 2015–2020, 19.2–22.7% of IMD cases each year resulted in death, but this fell to 12.5% in 2021 (Fig. S1 in the Supplementary Material) [14,15,16,17,18,19,20].

IMD Serogroups

Using laboratory surveillance data, serogroup B was the dominant serogroup responsible for IMD in Colombia during 1988–2014, but since 2015, serogroup C has been dominant (Fig. 5; Fig. S2 in the Supplementary Material [21, 22]). Serogroup Y was infrequently detected before 2003 but was the most common serogroup in 2006 and 2008. Since 2018, the number of cases of serogroup B and C appear to be decreasing, but the number of serogroup Y cases has remained constant (Fig. 5), resulting in an increasing trend in proportion to the other serogroups (Fig. S2 in the Supplementary Material).

Fig. 5
figure 5

IMD casesa from laboratory surveillance (1987–2009 [21]; 2010–2020 [22]), by serogroup and year. aThere were also 4 cases of serogroup A (2 in 1987, 2 in 1989), 2 cases of serogroup X (1 in 2008, 1 in 2011), and 18 non-typeable cases (2 in 1995, 2 in 1996, 3 in 1997, 1 in 1999, 1 in 2003, 1 in 2007, 2 in 2017, 1 in 2018, 3 in 2019, 1 in 2020, 1 in 2021). IMD invasive meningococcal disease

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During 2015–2020 combined, serogroup C was dominant, overall (220 of 417 cases [52.8%]) and in each age group (40.0–57.1%; Fig. S3a in the Supplementary Material). This was followed by serogroup B [65 cases in total (15.6%)], which was more dominant in the younger population, accounting for 13.8% of IMD cases among those aged 10–59 years to 27.1% among those aged 1–4 years, compared to only 3.2% among those aged ≥ 60 years (Fig. S3a in the Supplementary Material).

Within the 10–59-year age group, during 2010–2021 combined, serogroup C was the dominant serogroup, overall [96 cases in total (52.2%)] and in each age group (47.4–59.4%; Fig. S3b in the Supplementary Material). This was followed by serogroup B, which accounted for 65 IMD cases in total (35.3%) and 25.0–39.4% across age groups.

IMD by Department

During 2010–2021 combined, the majority of IMD cases (for all ages combined) were reported in Bogotá (31.9%), Antioquia (21.7%), Valle del Cauca (11.8%), and Bolívar (8.7%) (Fig. S4 in the supplementary material [22]). When taking department population sizes into account (averages of 2010–2021 [28]), the highest 12-year cumulative incidences were in Risaralda (2.44 per 100,000), Bogotá (2.41 per 100,000), and Bolívar (2.37 per 100,000), followed by Antioquia (1.90 per 100,000) and Norte de Santander (1.54 per 100,000) (Fig. S4 in the Supplementary Material [22, 28]). Approximate mean annual incidences during this 12-year period were 0.20 per 100,000 in Risaralda, Bogotá, and Bolívar, 0.16 per 100,000 in Antioquia, and 0.13 per 100,000 in Norte de Santander.

IMD by Socioeconomic Status

In the city of Cartagena, we analyzed 42 notified IMD cases (32 confirmed by culture, 4 by polymerase chain reaction, 4 by autopsy, and 2 were probable; 64.3% male; median [range] age 9 [0.1–60] years) during 2012–2017. Among these 42 cases, 17 patients died, for an overall lethality of 40.5% (Table 1 [33]). Most cases (35.7%) and deaths (47.1%) occurred in the 5–14 years age group, with 28.6% of cases and 23.5% of deaths occurring in children aged < 5 years.

Table 1 IMD cases and deaths during 2012–2017 by SE category in Cartagena
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Most of the cases (54.8%) occurred in people who lived in low–low SE status neighborhoods, with 7.1%, 21.4%, and 16.7% cases in low, medium–low, and unknown SE status neighborhoods, respectively (Table 1). Most IMD cases occurred in the neighborhood of Olaya (n = 14), with a maximum of two cases in each of the other neighborhoods.

Hospitalization duration increased with SE status (median 3 days for low–low, 10 for low, 13 for medium–low) (Table 1). As shown in Fig. S5a and b in the Supplementary Material, median hospital durations were 3 and 13 days in the low–low/low and medium–low SE neighborhoods, respectively. Fig. S5c in the Supplementary Material shows box-whisker plots for the hospitalization durations in each SE category. The results of the Wilcoxon rank sum test with continuity correction showed that W = 67.5 and p = 0.06 for the comparison of hospitalization durations in the medium–low versus low–low/low SE status neighborhoods.

Lethality was highest for those in low–low SE status neighborhoods (52.2% compared to 0% in low and 33.3% in medium–low SE status neighborhoods; Table 1). As shown in Fig. S6 in the Supplementary Material, eight patients in low–low SE status neighborhoods died without being admitted to hospital, with a further four dying after only 1–3 days of hospitalization.

Discussion

The present study describes the most recent epidemiology of bacterial meningitis and IMD in Colombia. The key findings of the study are: (1) IMD and other bacterial meningitis cases decreased in 2020 and 2021 relative to 2015–2019; (2) IMD incidence and IMD mortality incidence (per 100,000 population) were highest among infants aged < 1 year, followed by children aged 1–4 years; (3) since 2015, serogroup C has been responsible for the majority of IMD cases, overall and in each age group; (4) Bogotá and Antioquia had the highest numbers of IMD cases, while Risaralda and Bogotá had the highest incidences of IMD (per 100,000 population); and (5) low–low SE status neighborhoods had the highest burden of IMD (cases and deaths) and the shortest median hospital stay.

We report cases of confirmed bacterial meningitis for 2015–2017, but cases of confirmed bacterial meningitis or other IMD for 2018–2021, as that is what was included in the event reports [14,15,16,17,18,19,20]. Laboratory surveillance results show that 66% of IMD cases during 2015–2017 were meningitis, 24% were sepsis, and 10% were other IMD [22], hence Fig. 1 is missing a number of cases of non-meningitis IMD during 2015–2017. Regarding the lower numbers of IMD cases during 2020 and 2021 compared to 2018–2019 (52 and 32 vs. 108–116), this was likely due to non-pharmacological measures that were implemented to prevent the spread of coronavirus disease 2019 (COVID-19), e.g., reduced social contact and face masks, which also reduced the spread of N. meningitidis and other pathogens [19, 20]. However, following the relaxation of these measures, cases of IMD and other transmissible diseases are likely to increase [8]. Indeed, there were 54 confirmed cases of IMD in Colombia in 2022 [34] and 64 cases in the first 32 weeks of 2023 (i.e., 104 over the year if a constant rate is assumed) [35].

In the current study, most IMD deaths (among confirmed cases) were in children aged < 10 years (34.6%), followed by 10–19 years (22.0%), then ≥ 60 years (15.0%). Colombian data from 2005 to 2011 also showed that most IMD deaths (among probable cases) were in young children (< 5 years: 29%), but it is difficult to compare our results to the earlier data as their age groupings were different, so 44% of IMD deaths were among people aged 15–59 years, but this includes a large proportion of the population [13].

In the US, meningococcal vaccination is targeted towards adolescents and at-risk individuals [36]. Adolescents tend to have the highest rates of nasopharyngeal carriage (e.g., 23.7% of 19-year-olds in a 2010 meta-analysis [37]), increasing the risk of transmission within and from this age group. Vaccinating adolescents can therefore also help to protect other age groups [7, 8]. However, meningococcal nasopharyngeal carriage studies in Colombia have reported much lower carriage rates of 6.9% among 15–21-year-olds in Bogotá in 2012 [38] and 1.9% among 11–25-year-olds in Cartagena in 2019 [39]). In the current study, the highest burden of IMD during 2010–2021 was seen among infants aged < 1 year, with a mean incidence of approximately 1 per 100,000 and a mean mortality of around 0.3 per 100,000. This was followed by children aged 1–4 years, in whom the mean incidence was around 0.2 per 100,000 and mortality was approximately 0.1 per 100,000. Therefore, in Colombia, a vaccination strategy mainly targeting infants and young children is likely to be most beneficial to prevent IMD-related disability and death. Infant vaccination has already been implemented in various countries, including Chile (MenB and MenACWY) [10], Cuba (MenBC) [6], Brazil (MenC routinely, but MenACWY for high-risk infants) [6], and Argentina (MenACWY), which also recommends adolescent MenACWY vaccination [9].

Serogroup B was the dominant serogroup in Colombia until 2014, but serogroup C was dominant in all age groups examined during 2015–2020. The high numbers of serogroup C IMD cases during 2016–2019 (Fig. 5) may be due to continuous outbreaks. Serogroup B continues to be responsible for various outbreaks in Colombia, including six IMD cases in 2012 in children (aged 1.5–11 years) in a low-income neighborhood in Cartagena, of whom three died [40]. These cases were associated with estimated costs of US$735 for outbreak control, $3,935 for disease surveillance, and $4,921 for hospital care (tests, intensive care unit, regular ward, drugs, and procedures) (2011 US dollars) [40]. There have also been other documented outbreaks of serogroup B IMD in children and adolescents in Cartagena during 2010–2015. A later serogroup B outbreak affected three children (aged < 5 years) in Magdalena in 2018 [41]. This was managed by vaccinating 49 direct contacts and giving prophylaxis to 69 health personnel [41]. Six small outbreaks were reported by INS in 2018 in six different departments [17]. There were four serogroup C and two serogroup B outbreaks. Three were in military forces, two in the community, and one in a prison [17]. A further eight small outbreaks were reported by INS in 2019, of which three were serogroup C, three serogroup Y, and two unknown [18]. Four of these occurred in the military, two in the community, one in a prison, and one in a migrant population [18]. Soumahoro et al. [42] recently concluded that emergency mass vaccination in response to outbreaks was costly, and hampered by difficulties obtaining sufficient doses, issues with consent, and poor uptake; hence routine meningococcal vaccination is an attractive alternative. In Colombia, this could perhaps best be targeted to the departments with the highest IMD incidences and to low SE status areas in order to reduce the public health and social impact of IMD.

Serogroup Y was very infrequently detected in Colombia before 2003, but in 2006, it was the most common serogroup detected (Fig. 5), likely due to an outbreak among adolescents. Interestingly, although the numbers of cases of serogroup B and C decreased dramatically from 2019 to 2020/2021, serogroup Y did not decrease, which increased its relative importance (Fig. S2 in the Supplementary Material). Serogroup Y has also been the most common serogroup during the first 32 weeks of 2023 [35].

Unfortunately, molecular characterization of IMD isolates is not included in the Colombian surveillance program [43]. However, a study of 25 serogroup B isolates from Cartagena during 2012–2014 reported that 68.0% were B:10,15:nt phenotype associated with clonal complex ST-41/44, with various other phenotypes making up the remainder [44]. Another study of 193 Colombian IMD isolates from 2013 to 2016 reported that serogroup C and B were dominant (47.9% and 41.7%, respectively), with serogroup Y accounting for 9.4% [45]. A total of 15 clonal groups were identified [of which serogroup B sequence type (ST)-9493 was most common) and 14 clonal complexes (cc) (mainly ST-11 cc, ST-32 cc, ST-35 cc, and ST-41/44 cc) [45]. Further study of the 34 serogroup B ST-9493 isolates showed that the most common alleles were porin A 17 and porin B 44, while the most common peptides were factor H binding protein (fHbp) 2.24 and neisserial heparin binding antigen 10 [43]. It may be beneficial to perform genomic surveillance in Colombia in order to detect new clones [43]. The Sociedad Latinoamericana de Infectologia Pediatrica (SLIPE; Latin American Society of Pediatric Infectology) has recently highlighted the importance of active surveillance of IMD cases, along with recommending carriage and pharmacoeconomic studies and potentially the use of vaccines [8].

Regarding IMD cases by department during 2010–2021, Bogotá and Antioquia had the highest numbers of IMD cases (179 and 122, respectively), accounting for over half of the cases during that time, and some of the highest 12-year incidences (2.41 and 1.90 per 100,000, respectively). This is not surprising, as Bogotá is Colombia’s densely populated capital and has most of the healthcare facilities, while Antioquia is home to the large urban city of Medellin. Bolivar and Risaralda had similar 12-year incidences (2.37 and 2.44 per 100,000), but had much lower numbers of IMD cases (only 49 and 23, respectively).

In the SE status analysis, for which Cartagena was chosen because of the 2012 outbreak in this city [40], the low–low SE status neighborhoods had the highest number of IMD cases, the most IMD deaths, and the highest lethality, but the shortest median hospital stay (which approached significance for low–low/low vs. medium–low). Over half (52.2%) of the IMD patients from low–low SE neighborhoods died after a maximum of 3 days of hospitalization, which could reflect limited access to healthcare and a longer time with symptoms and disease progression before accessing healthcare, thus increasing the severity of the outcome. Indeed, income-related inequalities in barriers to seeking health services have previously been reported to be higher in Colombia than in three other Latin American countries (El Salvador, Paraguay, and Peru) [46]. The medium–low SE status neighborhoods had a lower lethality and a longer median hospital stay, which could imply that people in these neighborhoods sought healthcare more quickly. Interestingly, a previous study in Colombia reported that departments with higher inequality had significantly higher meningitis incidences [47]. Studies in England have also shown that deprivation is associated with increased risk of meningococcal disease [48, 49]. Overall, these differences imply disparities in access to healthcare and inequity by SE status that deserve to be addressed.

The World Health Organization and the Pan American Health Organization both recently launched roadmaps to defeat/curb meningitis by 2030, due to its potentially devastating sequelae and high lethality [50, 51]. The aims include the elimination of bacterial meningitis epidemics and a reduction in vaccine-preventable bacterial meningitis cases [50, 51]. Suggestions include new affordable vaccines, high immunization coverage, and improved disease surveillance [50]. The latter was also highlighted for strengthening in Latin America in 2015, with a focus on improving laboratory capabilities, communication, etc. [52]. Of note, IMD incidences in Colombia using data from laboratory surveillance were consistently lower than those from event reports. However, the difference seemed to improve over time, potentially reflecting improvements at both system and laboratory testing levels.

Limitations

There are a number of limitations that are inherent to surveillance systems, especially passive ones, including underreporting, lack of representativeness, and lack of timeliness [53]. According to national guidelines, all IMD samples captured by the national surveillance (i.e., SIVIGILA) should be sent to a laboratory for testing [54]. However, IMD incidences were lower by laboratory surveillance than by event reports, showing that there is room for improvement in Colombia, which could help to strengthen surveillance and evaluate the impact of interventions. Given this discrepancy, we requested certain data from the INS under the law of transparency to cross-check and validate the data from the publicly available reports. We also noted various inconsistencies within and between the various reports, which could be either editing errors or missing data. There were also some data that we were unable to obtain.

For the SE status analysis, the sample might be biased towards more severe IMD patients who required healthcare and hospital admission, and mild cases might not be captured. It was also difficult to compare IMD across the whole range of SE status neighborhoods as there were no IMD cases in medium, medium–high, or high SE status neighborhoods, although it should be noted that < 10% of the population lived in such neighborhoods in Cartagena. Lastly, clinical data were extracted primarily from medical histories.

Conclusions

Although IMD cases in Colombia were reduced during 2020 and 2021, this was likely due to measures put in place to slow the spread of COVID-19, and recent evidence shows that IMD rates are now rising again. The highest incidence and mortality incidence were observed among infants aged < 1 year, and the highest incidences of IMD were in Risaralda and Bogotá, while most cases were in Bogotá and Antioquia. The majority of IMD cases since 2015 have been serogroup C, followed by serogroups B and Y, hence MenACWY and MenB vaccination could be beneficial in Colombia, particularly in the most affected departments. We also noted that people living in low SE status neighborhoods were disproportionately affected by IMD, which could provide another opportunity to target vaccination in order to reduce the impact of IMD, improve public health, and reduce inequality.