Estonia not in a hurry to administer third doses

While more countries are opting for the third vaccine shot, the Estonian National Immunoprophylactic Expert Committee finds that there is not enough hard data on the effectiveness and safety of third shots. PHOTO: Mailiis Ollino

More and more countries are opting for third vaccine shots. People belonging to risk groups will get their third vaccine shots in Germany and France in September. Israel recently announced as much. Estonia sees no need for third jabs yet.

Israel said in late July that it will immunize people over 60 with their third dose of vaccine. The Estonian National Immunoprophylactic Expert Committee finds that there is not enough hard data on the effectiveness and safety of third vaccine shots. Scientists say that action cannot be taken without research to support it and that countries may be hurrying out of fear or trying to seize favorable opportunities.

Who, when and why in need of answers first

Head of the Estonian COVID-19 Scientific Advisory Council Irja Lutsar said that the questions of who, when and why need to be answered when talking about the third jab. “We cannot decide this matter without research,” she said.

“We do not yet know the side-effects of a third dose or whether it helps boost the number of antibodies. We would also need to know how long after the second should we administer the third shot,” Lutsar said, adding that there is no such information available in the world today.

Lutsar said that some studies show a third dose can hike the number of antibodies against the original (Wuhan strain) and Delta variants of the virus and it is possible a three-shot cycle could provide stronger immunization protection. “But whether such a scheme is more clinically effective against light infection and whether it has comparably modest side-effects remains unknown.”

The professor said that revaccination will prove necessary should immunity achieved through vaccination or recovering from the virus weaken over time or when new strains of the virus develop that are more resistant to existing vaccines. “Unfortunately, we will not know without clinical trials as we have no effective and universal biomarker for gauging immune response,” Lutsar said. Molecular biologist Madis Metsis told Postimees that a third shot would at the very least require studying the number of antibodies produced in as many age groups and at different times as possible. “We should look at how antibodies have been forming in different age groups and using different vaccines since December of last year and how stable they are. And if we see the number of antibodies going down, we could use that to predict when a new dose should be administered,” Metsis said.

Pfizer favorable for Israel

Metsis believes Israel is injecting third doses because of its special relationship with pharmaceutical giant Pfizer and because it can get vaccines cheap. He added that the country decided to administer third doses because the infection rate is going up again. “Pfizer’s sales turnover has exceeded €4 billion because of their vaccine, and it is only natural they want to keep selling their product,” Metsis found.

Epidemiologist Kuulo Kutsar said that no studies have recommended third doses, not to mention the world’s leading vaccinology and epidemiology centers, including the World Health Organization.

Head of the Estonian COVID-19 working group Marek Seer assured that the advisory bodies are keeping an eye on the revaccination topic. Right now, we know that the two-dose cycle is effective for about one year. “But we stand ready to react should new information come to light,” Seer added.