London School of Hygiene & Tropical Medicine

The COVID-19 pandemic has brought human activity to a standstill and now threatens to undermine routine immunisation programmes. On 26 March, the World Health Organization recommended that while routine immunisation programmes should continue, mass vaccination campaigns should be temporarily suspended because they could increase the spread of the virus in communities. 

Scientists at the London School of Hygiene and Tropical Medicine (LSHTM) have weighed up the health benefits of continued routine infant immunisation delivery against the risk of COVID-19 infections in Africa.

Funded by Gavi, the Vaccine Alliance and Bill & Melinda Gates Foundation, they estimated the impact of continued routine immunisation in comparison to the associated excess risk of coronavirus infection and further COVID-19 deaths in the household of the vaccinated child.

Their results are preliminary but striking: if routine immunisation was continued, for each excess COVID-19 death due to an infection acquired during the vaccination visit (predominantly among elderly household members), they forecast around 29 to 347 future child deaths could be prevented. Without vaccination these deaths could result from a range of diseases including measles, yellow fever, pertussis, meningitis, pneumonia and diarrhoea. 

Kaja Abbas, Assistant Professor in Disease Modelling at LSHTM and corresponding author on this study said: “In these difficult times, tough decisions need to be made by countries with limited health resources. They have to weigh up the pros and cons of immunisation. Is the health system able to carry out vaccination in the midst of this pandemic? Our research suggests that health benefits of deaths prevented by sustaining routine childhood immunisation in Africa far outweighs the excess risk of COVID-19 deaths associated with vaccination clinic visits.”

This is working on the assumption that in the coming months, all African countries will be as affected by COVID-19 as non-African countries have been early on in the pandemic. The estimate also assumes that there are no efforts to go back and vaccinate, or “catch-up” children who were not vaccinated as scheduled during a suspension, and that without a suspension, routine immunisation would reach as many children as it would otherwise during the pandemic.

The researchers point out that those who are maintaining physical distancing to stop the spread of COVID-19 are also at reduced risk of other infections, although they don’t expect such measures to work for especially contagious diseases such as measles or pertussis. But once physical distancing measures are relaxed, without the continuation of routine immunisation there would be millions of unvaccinated children vulnerable to deadly diseases.

If countries do decide to continue with routine immunisation during the COVID-19 pandemic, they will need to work out ways to implement physical distancing measures and infection control precautions. For example, between other families waiting or health care workers, or on public transport when travelling to the site. Vaccinators will be at high risk of infection because of the sheer numbers of people they will be coming into contact with, and will need to maintain stringent standards of infection prevention such as wearing suitable personal protective equipment and frequent hand washing.

Stefan Flasche, Associate Professor at LSHTM and senior author on this study said: "If routine childhood immunisation services get disrupted, an immunisation campaign to reach the unimmunised children, once feasible to conduct again, could help reduce the risk from vaccine-preventable diseases.

“However, even with such a campaign, we estimate that the benefit of continued routine childhood vaccination outweighs the risks of being infected with COVID-19 during the vaccination visit. This is particularly true for the vaccinated children who themselves are at relatively low risk for COVID-19, but at high risk for diseases like measles or pertussis.”

The authors acknowledge limitations of their work, including their focus on the delivery of infant immunisation for certain, but not all, diseases. They also assume contact-reducing measures are in place and are sufficient to reduce transmission to flatten the curve, as well as the risk, and hence potential disruption to health services, lasting for six months.

**This work has not yet been peer-reviewed**

Publication

K.M. Abbas, S.R. Procter, K. van Zandvoort, A. Clark, S. Funk, T. Mengistu, D. Hogan, E. Dansereau, M. Jit, S. Flasche, CMMID COVID-19 Working Group. Benefit-risk analysis of health benefits of routine childhood immunisation against the excess risk of SARS-CoV-2 infections during the COVID-19 pandemic in Africa. LSHTM CMMID Repository.