WHO and EMA doubt need of repeated booster vaccination

WHO and EMA doubt need of repeated booster vaccination
Credit: Belga

A vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be sustainable, WHO's Director-General said on Thursday.

Speaking at the meeting of the IHR Emergency Committee, Dr Tedros Adhanom Ghebreyesus also repeated his warnings against politicisation, nationalism, and disinformation.

“This toxic combination has hampered the response, fueling the transmission and evolution of the virus, and hampering equitable access to the tools to prevent, detect and treat it. As a result, many countries cannot meet basic baseline needs or modest targets.”

More than 9.4 billion vaccine doses have now been administered globally, he said.  But 90 countries did not reach the target of vaccinating 40% of their populations by the end of last year, and 36 of those countries have not yet vaccinated 10% of their populations. More than 85% of the population of Africa – about one billion people – is yet to receive a single dose of vaccine.

“We cannot end the acute phase of the pandemic unless we work together to close these gaps,” he underlined.

He also referred to the Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC), a group of experts established by WHO in September last year to review the implications of variants of concern on vaccines.

This week, the expert group said that more vaccines will be needed that have a greater impact on preventing infection and transmission, as well as severe disease and death.

Until such vaccines are developed, the composition of current COVID-19 vaccines may need to be updated, to ensure they continue to provide WHO-recommended levels of protection against infection and disease. A vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be sustainable, according to the group.

The group also emphasised that while some countries recommend boosters, the immediate priority for the world is accelerating access to primary vaccination, particularly for groups at greater risk of developing severe disease.

The latest statement by WHO adds some clarity to the information given earlier this week at a press briefing by WHO/Europe. In the current situation, the highly transmissible Omicron variant is surging and has become the dominant variant. While the efficacy of primary vaccination has decreased, boosters has resurrected the immune defence.

“Every country needs to proceed with completing the primary vaccination and to protect its vulnerable population with both primary vaccination and boosters,” according to WHO/Europe. That does not mean that a country can “booster” its way out from the pandemic.

The unsustainability of a strategy based on repeated booster doses is also shared by the European Medicines Agency. At a press briefing on 11 January, Dr Marco Cavaleri, head of the agency’s vaccines strategy, said that vaccines continue to work and that the protection is increased after a booster shot, especially against serious illness.

Omicron is a highly divergent variant with a high number of mutations, including 26-32 mutations in the spike protein, some of which may be associated with humoral immune escape potential and higher transmissibility. More precise data are still needed to fully characterise the Omicron variant, Dr Cavaleri said.

Furthermore, there are not yet data to support an approach of booster shots each 5 – 6 months of a vaccine which has been developed against previous variants, he added. A main concern is that the immune defence might be overloaded. Another concern with repeated boosters is “vaccine fatigue”.

A more long-term and global solution is to develop a multi-variant vaccine which will be effective against future variants of COVID-19 and which will not have to be taken so often.

The Brussels Times

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