Covid-19 booster shots: What Israel’s decision to administer third vaccine dose means for the world

Israel has recently started inoculating the country’s elderly residents with compromised immunity with a third dose of Pfizer-BioNTech’s Covid-19 vaccine. However, after meeting with Pfizer’s chief scientific officer on Monday, officials in the United States said more data was required to determine if a third dose would be necessary. The developments come amid increasing concerns over breakthrough infections among fully vaccinated people and debate over a booster shot.

Israel’s move to roll out booster shots comes amid reports of rising breakthrough infections. A New York Times report that compared datasets on vaccinated people from Israel Health Ministry and Pfizer’s own laboratory suggests that immunity in those with both vaccine doses is waning after six to eight months. There have also been reports of the elderly, the earliest to be vaccinated, being more infected now. Israel has also released a list of people eligible to get booster shots. It has prioritised heart, kidney, and lung transplant recipients and those with weak immunity such as cancer patients. The country now hopes to administer the booster shots to these groups and shore up their immunity to prevent further breakthrough infections.

With one of the fastest vaccine rollouts in the world, having inoculated 57% of its population with both doses, Israel has reported a surge in recent times. Daily infections have risen from single digits a month ago to average at 452 cases per day. The spike has coincided with the increased transmission of the Delta variant, attributed to have caused over 90% of the cases, as well as reports of lower effectiveness of the Pfizer-BioNtech vaccine against it.

Ran Balicer, chair of the country’s national expert advisory team on Covid-19, however, feels there still wasn’t enough conclusive evidence to suggest immunity was waning in vaccinated people. He said cases were rising as restrictions had been lifted and people were not following norms.

On its part, Pfizer-BioNTech has said it was working on a vaccine version that would target the Delta variant. Although yet to be peer-reviewed or published, its study shows antibodies rising significantly if the booster shot is administered within six months of the second dose. The company said the data would be submitted to the US Food and Drug Administration (FDA) shortly. Admitting that the vaccine’s effects wane over time, the company said a third dose might be needed within six to 12 months following full vaccination. It also said studies had shown that a third shown had led to a nearly five- to 10-fold jump in antibody levels when compared to the second dose months earlier. CEO Albert Bourla had earlier said a booster shot might be needed to maintain the highest levels of protection.

Despite Pfizer’s statement, the US FDA and the US Centres for Disease Control and Prevention (CDC) released a statement arguing that there was no need for a booster shot yet. It added that they were engaging in science-based, rigorous process on if or when a booster shot might be necessary, taking into account clinical trial data, laboratory data, and cohort data. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, also lent support to the decision, adding that the American people should be taking their advice from the CDC and the FDA. The Department of Health and Human Sciences also issued a statement and said fully vaccinated Americans did not need a booster shot.

As debates intensify over a booster shot, certain quarters are already pushing back at the idea. Most that have objected to a booster dose have highlighted the need for vaccine equity, shortage of doses in some countries, as well as the need to inoculate most people first. The World Health Organization’s Chief Scientist Dr. Soumya Swaminathan pointed out that millions of additional shots would be needed with more high-income countries mulling booster shots. This would deprive several other nations access to vaccines.

Scientists have also said manufacturers of all vaccines being administered only have an Emergency Use Authorisation and the US FDA should turn its attention on first granting full approval. This would allow the manufacturers to directly market and distribute their vaccines. There is also growing fear that the data on reduced efficacy, breakthrough infections, as well as the need for a booster shot might end up promoting greater hesitancy among the yet-to-be-vaccinated population.