Vaccine boosters: Why the US should listen to Israel

Vaccine boosters: Why the US should listen to Israel
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One of my friends who comes to me for medical advice is over 70 years old, slightly overweight, and scored fairly low on the spike antibody protein test — an indirect measurement of immunity due to the COVID-19 vaccines, though it is neither sensitive nor specific for that immunity. The test simply indicates if you have a smattering of antibodies around against the spike protein of the virus, but not whether they are functional at eliminating it from your body or not. 

In other words, if your results are high, it is probably a good sign, but if they are low, it doesn’t give you the quick answer you want. You could still have plenty of more specific neutralizing antibodies which block the virus, immune T-cells to gobble up viral particles, and memory plasma cells in your bone marrow ready to respond quickly to a viral challenge. So, as to whether he should get a booster shot based on the results of his antibody test, I don’t have an immediate answer for my friend.

Another friend, 68, has a thick heart (cardiomyopathy) and also wants to know if he should get a COVID booster. Both friends had their vaccines in February, and both are concerned by the Israeli data about the Pfizer vaccine’s effectiveness diminishing overtime in its battle against the delta variant (in their age group).


Israel has been a kind of enormous laboratory for Pfizer, giving its vaccine to millions and meticulously following results and all data. Though we in the U.S. have a tendency to rely on our own data before making health policy decisions, it is time for us to pay very close attention to Israel’s data. Though data released from Pfizer in over 40,000 patients released last Wednesday showed that protection against severe illness remained at greater than 95 percent at the six-month mark, Israel’s Health Ministry last Thursday released data suggesting that people vaccinated in January had just 16 percent protection against infection now, while in those vaccinated in April the effectiveness was at 75 percent. Other analyses of the Israeli government’s national health statistics show the immunity dropping to 39 percent

This is particularly troubling when you consider that the vaccines are not as effective against the delta variant and its mutations to the spike protein to begin with.

So, what is holding us back here in the U.S. from immediately giving out boosters to those who are immunocompromised and the elderly,  which is what Israel is doing? And why can’t we develop a definitive immune titer test the way we have for other vaccines, including Hepatitis B? 

Also, the booster question is a moving target, meaning that the more of the virus there is around (in this case, the delta variant), the more likely it is that you, a fully vaccinated person, will encounter it. And it is the direct prolonged exposure that tests the mettle of the vaccine; 85 percent effective against infection means that 15 out of 100 people will get sick if they are challenged by the virus. That’s still an extremely high-performing vaccine.

But because these encounters are becoming more frequent the more the delta variant spreads, the more likely it is that a booster will be recommended in groups with decreased immunity. I spoke with Centers for Disease Control and Prevention (CDC) Director Rochelle WalenskyRochelle WalenskyCDC director on kids trick-or-treating: 'If you're able to be outdoors, absolutely' Walensky: 'We don't necessarily have the answer' for annual boosters Pfizer CEO predicts 'normal life' within a year MORE about this last week, and she said that, in poring through the data on immunity and case occurrences, there was not yet a “signal” that immunity is waning or has waned in those at a higher risk (including the immune-compromised and the elderly) who received the vaccine when it first became available in late December and January. 


But I have had several below-the-radar conversations with hospital infectious disease experts who tell me that they are seeing signs of waning immunity in higher-risk groups who have mounted less of an immune response over several months. It appears likely that over the next few weeks doctors will be asking for a booster here.

In the meantime, my phone is ringing off the hook with nervous questions about whether to get a booster or not. The official answer is still "no, not available yet," although I suspect some of my elderly or chronically ill patients might be finding ways around that.

I am waiting, but I expect the U.S. soon will follow Israel's example on booster shots. 

Marc Siegel, M.D., is a professor of medicine and medical director of Doctor Radio at NYU Langone Health. He is a Fox News medical correspondent and author of the new book, "COVID; the Politics of Fear and the Power of Science."