If COVID boosters are so effective, why isn’t everyone getting one?

Hebrew University epidemiologist and public health physician Prof. Hagai Levine said that there is not necessarily proof that a third shot is needed for everyone.

 Medical staff receive their third COVID-19 vaccine shot at Meir Medical Center in Kefar Sava, August 13, 2021. (photo credit: AVSHALOM SASSONI/FLASH90)
Medical staff receive their third COVID-19 vaccine shot at Meir Medical Center in Kefar Sava, August 13, 2021.
(photo credit: AVSHALOM SASSONI/FLASH90)

A Pfizer COVID-19 vaccine booster trial released last Thursday revealed some pretty spectacular data: It had a relative vaccine efficacy of 95.6% against the disease when compared with those who did not receive a booster during the period when the highly contagious Delta variant has been the prevalent strain.

In Israel, where nearly 3.9 million people have gotten the third shot, cases have declined from an average of more than 6,500 a day in September to around 1,600 in October.

But there are still 1.5 million individuals who received two doses more than six months ago and have still not gotten a booster shot.

“The Pfizer trial shows that the booster shot will increase this group’s protection against infection by 20 times,” said Eran Segal, a computational biologist at the Weizmann Institute of Science in Rehovot who has been advising the government. “Yes, three shots versus two means 20 times more protection.”

Moreover, in most countries, including the United States, if boosters are approved at all, they are only available to limited parts of the population, such as the elderly or people at the highest risk for contracting the virus or developing severe disease.

Jerusalem resident Phillip Brieff is seen getting the third COVID-19 booster shot at a Meuhedet clinic, on August 1, 2021. (credit: MARC ISRAEL SELLEM/THE JERUSALEM POST)Jerusalem resident Phillip Brieff is seen getting the third COVID-19 booster shot at a Meuhedet clinic, on August 1, 2021. (credit: MARC ISRAEL SELLEM/THE JERUSALEM POST)

So if COVID boosters are so effective, why isn’t everyone getting one?

The Pfizer trial included more than 10,000 participants over the age of 16, divided into two groups: third shot and placebo. The median time between the second and third dose was 11 months. Within an average of 2.5 months after receiving the booster, only five people developed symptomatic COVID-19. Some 109 people who did not receive the booster got COVID.

“We believe boosters have a critical role to play in addressing the ongoing public health threat of this pandemic,” said Pfizer CEO Albert Bourla. “We look forward to sharing these data with health authorities and working together to determine how they can be used to support the rollout of booster doses around the world.”

BUT HEBREW University of Jerusalem epidemiologist and public health physician Prof. Hagai Levine said Israel should not be so quick to push its “magic bullet” solution on other countries, which need to make the right decisions for themselves based on both culture and their epidemiological situation.

“I would not copy and paste our experience in other countries,” he said, adding that “Israel should be humbler. The pandemic fluctuates. This wave is decreasing in other countries without the booster shot. Giving the booster to everyone is not necessarily key.”

The devil is in the details, explained Prof. Nadav Davidovitch, director of Ben-Gurion University of the Negev’s School of Public Health and head of the Israeli Association of Public Health Physicians.

While Israel managed to inoculate 6.2 million Israelis with at least one dose of the vaccine, many other countries are still struggling to administer the first shot. In some places, even where vaccines are readily available, there could be fragmented healthcare systems, which means there is an uneven distribution that might need to be rectified before third shots can be considered.

Also, Israel vaccinated people much earlier than some other countries, which means it was the first to have data showing that the vaccines begin to wane between four and six months after the second shot – data that has now been replicated in other countries, including the US.

“In Israel, we have the unique situation: that a very large proportion of the population was vaccinated at the same time, so the impact of waning also comes at the same time, making the need for the booster shot much stronger,” Levine said.

In other countries, vaccine campaigns took longer and therefore waning across the community will also take more time.

FINALLY, there is still an issue of side effects, Davidovitch said. Although preliminary studies show the side effects of the booster are quite rare and generally not worse than the second dose, there is not necessarily enough data to be sure yet, and therefore this could also serve as a barrier to mass booster shots in some countries, he said.

Levine said while the Israeli Association of Public Health Physicians did not oppose allowing the booster shot for everyone in Israel when the decision was made, “there was not necessarily proof that it was needed for everyone.”

Israel was in a rush to get the booster shots started as the infection rate rose, he said. As such, the country did not use serological tests as a consideration before administering the booster to make a more informed decision about which parts of the population might need the third shot more than others.

“If countries have more time and their epidemiological situation is different, they may consider using serological testing as a tool,” Levine said. “They may also be able to have a more tailored approach to the booster shot.”

For example, while the vulnerable population – the elderly and people with underlying medical conditions – clearly requires a booster, he said, younger, healthier people may not need the shot.

“How many people died in Israel from COVID-19 who are young, healthy and received two Pfizer doses?” Levine asked. “Very, very few.”

The need to give a booster shot to people under 18 has not been proven yet, which is why the US Food and Drug Administration and the European Medicines Agency are waiting for more data, he said.

“My take is that if you do not need [the booster], wait,” said Prof. Cyrille Cohen, head of the immunology lab at Bar-Ilan University.

He admitted that boosters are a little bit of a game of chicken and egg. If a country needs it, it should start administering the booster. But if not, it should wait until it is necessary so that it can buy itself more time. After all, there is no indication of how long the third dose will last.

In the United Kingdom, for example, with Delta mutation AY4.2, no restrictions and early vaccination, it seems the booster should have been rolled out earlier.

“They waited too long,” Cohen said.

Will all countries eventually need the shot?

It is likely, Davidovitch said.

“I am confident that each country that does not give the booster is going to see a resurgence of cases,” he concluded.