HMO: Early vaccinees are twice as likely to catch COVID as later recipients

Latest research ‘definitely’ reinforces argument for giving boosters to the elderly, says lab chief at Leumit

Nathan Jeffay is The Times of Israel's health and science correspondent

Health care workers on duty taking swabs for coronavirus tests in Jerusalem, July 22, 2021. (Yonatan Sindel/Flash90)
Health care workers on duty taking swabs for coronavirus tests in Jerusalem, July 22, 2021. (Yonatan Sindel/Flash90)

People vaccinated before late February are twice as likely to catch the coronavirus than other inoculated Israelis, according to new research.

“We looked at tens of thousands of people tested in the month of June, alongside data on how long had passed since their second shot, and found that those vaccinated early were more likely to test positive,” Dr. Yotam Shenhar, who headed the research, told The Times of Israel.

“This definitely reinforces the argument for giving a third vaccine dose to the elderly.”

The report, published by the healthcare provider Leumit, comes on the heels of other Israeli studies that suggest a decreasing vaccine effectiveness, partly as a result of the Delta variant and partly because of the passage of time. However, British data indicates the Israeli studies may be overstating the case.

Data released by the Health Ministry on Thursday suggested that people vaccinated in January were said to have just 16% protection against infection now, while in those vaccinated in April the effectiveness was at 75%

The Leumit study looked only at the apparent waning of protection over time, and divided the vaccinated population into two based on inoculation dates, comparing early vaccinators to late vaccinators.

An Israeli youth receives a COVID-19 vaccine in Tel Aviv on July 6, 2021. (Jamal Awad/Flash90)

Shenhar, head of Leumit’s labs, acknowledged that the early vaccinators group includes many people who raced to get shots because they have underlying illnesses, which may make them more vulnerable to infection. But he said that could not fully account for the stark effect seen in the data.

Shenhar said the data should prompt the government to seriously consider booster shots for over-70s.

“Now we see vaccination effectiveness drops, so it seems we definitely need to think about a third vaccine,” he said. “We have started already by giving the immunocompromised, but in my assessment we need to consider giving third shots to everyone over 70 or 80. We shouldn’t wait long; we need to make a decision fast.”

If he were formulating policy, Shenhar said, he would “definitely” start giving boosters to elderly Israelis.

In his study, the apparent waning effect in immunity was felt across all ages. For all age groups, early vaccinators were 1.95 times more likely to be confirmed coronavirus positive. Among those aged 60-plus, early vaccinators are twice as likely to get infected. For those aged 40-59 early vaccinators are 2.1 times more vulnerable, and among under 39s they are 1.6 more likely to catch the coronavirus.

“In a previous analysis we showed that as time passes since the vaccine, the level of antibodies drops at a rate of about 40% per month. This new study builds a clearer picture of the effect seen in the months after vaccination,” said Shenhar.

Israel has seen a dramatic rise in recent COVID-19 infections, with the daily caseload rising from several dozen to over 1,400 in recent days.

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