Coronavirus

Immunization during the COVID-19 pandemic: the WHO/Europe guidance

The COVID-19 pandemic (caused by the new SARS-CoV-2 virus) risks disrupting routine immunization activities in the countries of the European Region of the World Health Organization (WHO). This is due to both healthcare resources being shifted to the pandemic response and the social distancing measures currently in place, as some people could decide to postpone scheduled vaccinations for themselves or their children.

Immunization services are an essential component of health services. Any disruption of immunization services, even for short periods, would result in an accumulation of susceptible individuals and raise the risk of outbreaks of vaccine-preventable diseases (VPDs). Such outbreaks may cause deaths and increase the burden on health systems that are already strained by the response to the COVID-19 emergency. It is therefore essential to minimize this risk.

On 20 March 2020, WHO/Europe published the document “Guidance on routine immunization services during COVID-19 pandemic in the WHO European Region”. This document is designed to help countries make decisions regarding the continuing provision of routine immunization services during the pandemic, outlines key factors that they should take into account in their risk assessments, and provides guiding principles and considerations to conduct immunization activities under safe conditions.

According to the WHO, it is essential to maintain immunization sessions, especially the routine ones, as long as COVID-19 response measures allow. Any decision related to the operation of immunization services should be taken based on a detailed assessment of: VPD epidemiology, transmission scenario of COVID-19 and corresponding mitigation measures in place, and available resources. In particular, the following should be assessed:

1. Epidemiological risks of VPDs among the general population and specific vulnerable groups (What is the potential risk of an increased VPD occurrence? Review vaccination coverage and VPD surveillance data, including ongoing measles outbreak characteristics; special emphasis should be given to epidemic-prone VPDs and to halting any backslide in achievement of measles elimination or polio eradication).
2. Epidemiological situation of COVID-19 and related mitigation measures in place (What is the transmission scenario of COVID-19?).
3. Health system, characteristics and constraints of immunization services.
4. Availability of vaccines and logistics capacity (Are vaccines available in sufficient quantities?).

The impact and appropriateness of the chosen options should be monitored and periodically reassessed as the COVID-19 pandemic evolves. The current COVID-19 situation and health system capacities vary widely across the WHO European Region and are rapidly evolving. Therefore, approaches to sustain high levels of immunization coverage will also vary among countries. However, all countries should make every possible effort to maintain high levels of immunity among their populations. Considering that some disruption may occur, it is crucial to immediately start keeping a list of children who have missed their vaccine doses and develop an ad hoc action plan for catch-up immunization.

Key principles for immunization services

In its document, the WHO outlines the guiding principles for the provision of immunization services during the COVID-19 pandemic:

• Follow the existing guidelines (national guidelines, if available) on SARS-CoV-2 infection prevention measures during immunization sessions. Relevant programmatic considerations in limiting risk of SARSCoV-2 transmission during vaccination are provided in an annex to the WHO document.
• Prioritize primary series vaccinations, especially the measles-mumps-rubella (MMR) vaccine, polio vaccines and other combination vaccines.
• Avoid mass vaccination campaigns until the COVID-19 situation resolves.
• Vaccinate newborns (as per the national immunization schedule) in maternity wards.
• Prioritize pneumococcal and (during the winter) influenza vaccines for the vulnerable groups.
• Delay the introduction of any new vaccine/s in the national immunization schedule.
• Communicate clearly to the community and healthcare workers: the rationale for inclusion of immunization as one of the priority health services during the COVID-19 pandemic; the risks from VPDs; the benefits of vaccination.

The epidemiological, operational and contextual characteristics in each country are unique, and it would be impossible to determine one appropriate strategy for all situations. WHO/Europe provides an algorithm to help national authorities take decisions related to the continuing operation of immunization services. It also stresses the importance of maintaining and enhancing VPD surveillance to ensure that cases of vaccine-preventable diseases are identified at an early stage and properly managed.

The recommendations of the WHO Regional Office for Europe are reiterated in a second WHO document, entitled “Guiding principles for immunization activities during the COVID-19 pandemic”. This document points out that the high potential for VPD outbreaks makes it imperative for countries to maintain continuity of immunization services wherever they can be conducted under safe conditions.