Booster vaccination: only for those with weakened immune systems, says EU agency
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Booster vaccination: only for those with weakened immune systems, says EU agency

People queuing for a booster shot in Tel Aviv

There is no urgent need for booster doses of vaccines for fully-vaccinated individuals in the general population, according to a technical report issued yesterday evening by the European Centre for Disease Prevention and Control (ECDC).

The technical report also notes that additional doses should already be considered for people with severely weakened immune systems as part of their primary vaccination, if they do not achieve an adequate level of protection from the standard primary vaccination.

About a month ago, ECDC stated in a response to The Brussels Times that it had not yet issued any recommendations on booster vaccinations for COVID-19 given the lack of evidence that boosters are required as a measure for the general population.

The new report is still inconclusive on the need for booster vaccinations. ECDC emphasises that its intention is not to provide recommendations about the administration of additional doses of COVID-19 vaccines but rather to summarise current data in this area and outline options for consideration by public health authorities.

Despite a comprehensive overview of available research in both EU and non-EU countries, the ECDC concludes that there are still knowledge gaps and more research is needed to establish exactly when a vaccine booster might be needed.

In summary, evidence based on vaccine effectiveness and the duration of protection shows that all vaccines authorised in the EU/EEA offer a high degree of protection against COVID-19-related hospitalisation, severe disease and death, while about one in three adults in the EU/EEA are not yet fully vaccinated.

In this situation, the priority now should be to vaccinate all those who are eligible and have not yet completed their recommended vaccination course. To complement vaccination efforts, it is also crucial to maintain measures such as physical distancing, and hand and respiratory hygiene, and the use of masks, particularly in high-risk settings such as long-term care facilities or hospital wards with patients at risk of severe COVID-19.

ECDC underlines that it is important to distinguish between booster doses for people with normal immune systems and additional doses for those with weakened immune systems. Some studies report that an additional vaccine dose can improve the immune response in immunocompromised individuals, such as organ transplant recipients whose initial responses to vaccination were low.

In such cases, the option of administering an additional vaccine dose should now be considered. Consideration could also be given to providing an additional dose, as a precautionary measure, to older frail individuals, in particular those living in closed settings such as long-term care facilities.

In fact, based on the most recent available information, eight EU/EEA countries (Austria, Belgium, France, Hungary, Liechtenstein, Lithuania, Luxembourg, and Slovenia) are currently recommending the use of an additional vaccine dose or booster dose (i.e. third dose for two-dose schedule and second dose for single-dose schedule vaccines), while Germany is planning to implement this in the autumn.

Furthermore, a decision is currently being discussed in 13 EU/EEA countries. All protocols currently in place recommend an additional dose in immunocompromised or immunosuppressed individuals.

The subject of boosters or additional vaccine doses is evolving rapidly outside of the EU/EEA. The UK, for example, has published a report that outlines a booster programme that could begin in September 2021, the primary objective being to maximise protection in individuals most vulnerable to serious COVID-19 ahead of the winter months.

The report describes studies of vaccine effectiveness, including from the period when the Delta variant was dominant, and also considers the duration of immunity following natural infection. The report refers to findings in Israel – the first country to start a nationwide booster campaign – which now includes all age groups.

The Israeli studies, based on surveys of all residents of the country who became vaccinated compared to unvaccinated residents, looked into the effectiveness of vaccines received at different times of the year by people aged 60 years or older.

Interestingly, they showed that vaccine effectiveness against infection decreased from 73% for those who became fully vaccinated in the second half of March to 57% for those who became fully vaccinated during the second half of January.

There was also a decrease in the protection of the vaccine, Pfizer-BioNTech, against severe disease for the 60+ age group from 91% (95% CI: 85-95) to 86% (95% CI: 82-90) between those vaccinated four months before the study to those vaccinated six months before the study.

ECDC notes that the vaccination policies in Israel were different from other countries, as Israel used only one vaccine and had a three-week interval between the two doses, as was recommended by Pfizer. The Israeli study concludes that the vaccine seems to be highly effective even after six months when compared to the unvaccinated population. Yet the effectiveness of the vaccine does drop significantly in the months after vaccination.

Contrary to most EU countries, where the rollout of the vaccination campaigns was initially slow and only gathered speed in April, the vaccination of elderly people in Israel started already in December, which might explain why the immunity protection among the elderly age group has decreased since then.

Notwithstanding the findings in Israel, ECDC is of the opinion that the evidence of today indicates that there are no concrete signs in the EU/EEA of waning of immunity against severe disease, hospitalisation and death in any age group, therefore there is no urgent of administering additional vaccine doses to the general population.

That said, the agency clarified that this does not exclude that waning of protection against severe disease could occur in the future. Therefore, ECDC is continuing to closely monitor the situation and will update its assessment accordingly if needed.

Moreover, global vaccine inequality is a rising concern. The ECDC highlights the fact that the current global shortage of COVID-19 vaccines could be exacerbated by administering additional COVID-19 vaccine doses in EU/EEA countries.

ECDC refers to the recent WHO call for a moratorium on booster shots until at least the end of September 2021 in order to increase vaccine availability for low- and middle-income countries.

To this end, the WHO modified its position this week. In a statement on 30 August, WHO Regional Director for Europe Dr Hans Kluge described the epidemiological picture in the WHO European Region, comprising 53 countries, as mixed.

Regarding the need for third doses, he told The Brussels Times that they should not be provided as a ‘luxury’ item for the fit and healthy. “They should be prioritized for the most vulnerable and immunocompromised when there is evidence of waning immunity against severe disease and death.”

For example, emerging data shows that immunocompromised people should receive a third dose if they did not respond sufficiently to their initial doses or if they are no longer producing antibodies. Such groups would be exempt from the booster moratorium, according to Dr Kluge.

“If third doses are prioritized for those most at-risk, while global access to vaccines is increased – such as through increasing production and donating doses to COVAX – then they should not be seen as depriving others of their first doses. In short, we must do it all – increase vaccine uptake, increase vaccine production and increase vaccine sharing.”

Asked at today’s Commission press conference if the EU will have enough vaccine doses for booster vaccination of the general population if the need should arise later in Autumn or next year, a spokesperson referred to the new contract which was signed with Pfizer-BioNTech to guarantee the delivery of 1.8 billion doses between the end of this year and 2023.

That contract aims at ensuring continued access to vaccine doses for possible new variants in the future and for booster vaccination should the need arise, the spokesperson said. The Commission has also used its option to purchase an additional 150 million in 2022 from Moderna on behalf of all EU member states.

Note: The article has been updated to include clarifications from the ECDC and the European Commission.

M. Apelblat
The Brussels Times