Impact of COVID-19-related disruptions to measles, meningococcal A, and yellow fever vaccination in 10 countries

Abstract

SummaryBackgroundChildhood immunisation services have been disrupted by the COVID-19 pandemic. WHO recommends considering outbreak risk using epidemiological criteria when deciding whether to conduct preventive vaccination campaigns during the pandemic.MethodsWe used 2-3 models per infection to estimate the health impact of 50% reduced routine vaccination coverage in 2020 and delay of campaign vaccination from 2020 to 2021 for measles vaccination in Bangladesh, Chad, Ethiopia, Kenya, Nigeria, and South Sudan, for meningococcal A vaccination in Burkina Faso, Chad, Niger, and Nigeria, and for yellow fever vaccination in the Democratic Republic of Congo, Ghana, and Nigeria. Our counterfactual comparative scenario was sustaining immunisation services at coverage projections made prior to COVID-19 (i.e. without any disruption).FindingsReduced routine vaccination coverage in 2020 without catch-up vaccination may lead to an increase in measles and yellow fever disease burden in the modelled countries. Delaying planned campaigns in Ethiopia and Nigeria by a year may significantly increased the risk of measles outbreaks (both countries did complete their SIAS planned for 2020). For yellow fever vaccination, delay in campaigns leads to a potential disease burden rise of >1 death per 100,000 people until the campaigns are implemented. For meningococcal A vaccination, short term disruptions in 2020 are unlikely to have a significant impact due to the persistence of direct and indirect benefits from past introductory campaigns of the 1 to 29-year-old population, bolstered by inclusion of the vaccine into the routine immunisation schedule accompanied by further catch-up campaigns.InterpretationThe impact of COVID-19-related disruption to vaccination programs varies between infections and countries. Planning and implementation of campaigns should consider country and infection-specific epidemiological factors and local immunity gaps worsened by the COVID-19 pandemic when prioritising vaccines and strategies for catch-up vaccination.FundingBill & Melinda Gates Foundation and Gavi, the Vaccine AllianceResearch in contextEvidence before the studyWe searched PubMed for (COVID-19 OR coronavirus OR SARS-CoV-2) AND (child health intervention OR vaccin* or immuni*) AND (disruption OR suspension OR reduction) AND (indirect effect OR health impact) on January 14, 2021, with no language restrictions. We found 178 articles of which 13 articles were relevant. Six articles reported some empirical data on immunization disruption in Bangladesh, Japan, Kenya, Nigeria, Pakistan, Saudi Arabia, South Africa, Spain and Italy, and a survey study focussed on immunization disruption in low and middle-income countries. One article proposed using the WHO health systems framework to assess the effects of COVID-19 on immunisation programmes in South Africa, another study on leveraging systems thinking and implementation science to improve immunization system performance in Africa, and two studies were review articles. One modelling study focused on the indirect effects, including reduction in routine immunisation services, of the COVID-19 pandemic on maternal and child mortality in low-income and middle-income countries. Another modelling study focused on a benefit-risk analysis of routine childhood immunisation during the COVID-19 pandemic in Africa. We also found one other study in the grey literature that analysed the impact on SARS-CoV-2 infections as a result of fixed-post and door-to-door vaccination campaigns targeted at children under five years of age in an Ethiopia-like setting.Added value of this studyWe estimated the increase in cases and deaths caused by the disruption to immunisation services leading to outbreaks for measles, meningococcal A and yellow fever in 10 countries. The reduction in routine immunisation coverage among under-immunised cohorts of children has enhanced the risk of outbreaks which cannot be averted without catch-up vaccination. This can lead to an increase of 9.89% (0.91 additional deaths per 100,000 individuals, or 48,000 in total) across the three diseases from 2020 to 2030 in the countries considered. Results vary by infection and country, but generally most excess deaths are due to measles. Postponing campaign immunisation may not have a detrimental short-term health impact if campaign immunisation is implemented ahead of future outbreaks caused by these immunity gaps.Implications of the available evidenceThe COVID-19 pandemic has caused significant disruptions to routine services and vaccination campaigns and resulted in immunity gaps with potential to cause outbreaks in the affected populations. The short-term and long-term health impact differ between measles, meningococcal A and yellow fever vaccination and by countries based on the local epidemiological situation. Thereby, catch-up vaccination should be planned by considering the heterogeneity in population susceptibility across different countries to measles, meningococcal A and yellow fever outbreaks and implemented in time to prevent these outbreaks. The study findings can inform risk-benefit trade-off discussions around the timing of campaigns.

Estimating global and regional disruptions to routine childhood vaccine coverage during the COVID-19 pandemic in 2020: a modelling study

“…Despite disruptions to vaccination, in the short term the transmission risk of vaccine-preventable diseases might have been temporarily mitigated by mask use, physical distancing, and other types of preventive behaviours practised during the pandemic. As evidenced by past epidemics and modelling exercises, 45 , 46 substantive gaps in vaccine coverage increase the risk of vaccine-preventable disease outbreaks once COVID-19 prevention measures subside and individuals resume pre-pandemic social contact patterns. A recent study suggests a potential 10% increase in mortality from vaccine-preventable diseases as a result of pandemic-related disruptions to routine immunisation and other planned vaccination campaigns, 45 while other work has associated declines in doses with increases in polio cases in endemic countries.…”

“…As evidenced by past epidemics and modelling exercises, 45 , 46 substantive gaps in vaccine coverage increase the risk of vaccine-preventable disease outbreaks once COVID-19 prevention measures subside and individuals resume pre-pandemic social contact patterns. A recent study suggests a potential 10% increase in mortality from vaccine-preventable diseases as a result of pandemic-related disruptions to routine immunisation and other planned vaccination campaigns, 45 while other work has associated declines in doses with increases in polio cases in endemic countries. 6 Previous infectious disease outbreaks, such as the 2014 Ebola virus epidemic in west Africa, also led to large disruptions to routine immunisation and subsequent measles outbreaks.…”

Lessons for and from the COVID-19 pandemic response — An appraisal of guidance for the public health management of Invasive Meningococcal Disease

“…mask wearing, hotel quarantine, lockdown strategies) [ 1 , 2 ]. While responses to the COVID-19 pandemic have reduced the spread of IMD and other communicable diseases [ 4 , 38 ], they have also impacted vaccination programs [ 3 , 39 ] and may negatively impact outbreak management strategies. The current delay between increased understanding of disease transmission and actual implementation into public health guidance can have direct and immediate consequences for individual and population health.…”

SARS-CoV-2 infection risk during delivery of childhood vaccination campaigns: a modelling study

“…10 For vaccine campaigns, the risk of outbreaks as a result of postponing campaigns varies across settings and pathogens. 11 For some vaccines (e.g. meningococcal A), campaigns can be postponed in the short-term in many settings due to the persistence of immunity from past campaigns.…”

“…Previous modelling studies have demonstrated that the benefits of continuing routine immunisation likely outweigh the excess risk from COVID-19 but did not examine campaign delivery 10 . A recent study has examined risks of vaccine-preventable disease outbreaks (measles, meningococcal A, and Yellow Fever) associated with delaying immunisation campaigns, which varied across countries 11 . Another study assessed the risk of measles outbreaks in Kenya and found that although COVID-19 interventions also temporarily reduced the risk of an outbreak from measles immunity gaps, this risk rises rapidly once these restrictions are lifted highlighting the need to implement catch-up campaigns 12 .…”