Do You Need A Second Covid Booster Shot? Experts Are Divided.

Topline

Amid evidence of waning immunity and new Covid surges across Europe and Asia, a growing number of countries have started rolling out fourth doses of coronavirus vaccines—or are debating doing so— a topic that divides U.S. health experts and officials as they prepare for a possible upswing of cases driven by the BA.2 omicron subvariant and that could be impossible to implement in the U.S. without new federal funding.

Experts are divided on the need for fourth vaccine doses.

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Key Facts

Moderna asked the Food and Drug Administration to authorize a second booster dose of its Covid vaccine for all adults last Thursday, two days after Pfizer and BioNTech asked the regulator to greenlight an additional booster for people ages 65 and older, both citing evidence from Israel that shows decreased efficacy during the omicron surge.

Though research demonstrating waning immunity against omicron after the first round of immunization justifies the first booster shot for all adults, experts find the data less compelling when it comes to whether or not a second booster shot is warranted.

While a fourth dose appears to be beneficial at preventing severe disease in older or high-risk individuals, Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, told Forbes it wasn’t clear that younger groups (excluding those with high-risk conditions) “benefit much from even third doses.”

The key goal of vaccination should be reducing serious illness from Covid, Adalja said, adding that for “most people,” two shots of an mRNA vaccine “is sufficient protection.”

Professor Deepta Bhattacharya, an immunologist at the University of Arizona, told Forbes there was evidence vaccine effectiveness is “slipping against omicron” in some age groups—notably older people and kids between 5 and 11—and that vulnerable people who were boosted months ago “may want to get another dose,” but for anyone else “it’s a choice” and probably not needed.

Given low rates of transmission in most of the U.S. right now, Bhattacharya said fourth shots aren’t needed “immediately,” explaining that there “isn’t much sense in getting a shot during a period of relative calm” if effectiveness against omicron does wane rapidly.

Crucial Quote

“I believe the goal with a virus like this and the vaccine we have should be to prevent severe disease,” Adalja explained. “Targeted—not blanket, one-size-fits-all—booster policies are how to achieve it.”

Key Background

Regulators justified third coronavirus vaccine doses based on evidence the protection they provided against symptomatic infection waned over time, particularly in older age groups most vulnerable to severe outcomes. Reduced effectiveness against the now-dominant omicron variant of coronavirus further made the case for boosting. This case is not as clear cut for fourth doses. Countries including the U.K., Sweden, Israel and Denmark are offering the shots to immunocompromised and at-risk groups, including older age groups. Experts advising the government in Israel recommend making fourth doses available to all adults. U.S. officials have previously said fourth doses will not be needed, though later said they are monitoring emerging data to evaluate the need for additional boosters. According to the Washington Post, federal officials do not have the budget secured for fourth doses beyond Americans ages 65 and over. U.S. data does show diminishing protection against serious illness and hospitalization in the months after the booster, though Anthony Fauci, who heads the National Institute of Allergy and Infectious Diseases, said the shots are still providing robust levels of protection.

Tangent

Initial vaccine trials were not able to assess how durable the protection a vaccine provided was beyond a few months. While these trials favored mRNA shots by Pfizer and Moderna over the vaccine from Johnson & Johnson, Professor Dan Barouch, a vaccine researcher at Harvard Medical School, told Forbes its “durability has proven substantially better.” CDC data shows breakthrough rates to be “slightly higher for the J&J vaccine” than the Pfizer or Moderna shots during the delta surge last summer, but “these differences then narrowed over time,” Barouch said. “The lines “crossed” during the first week of December, and since then breakthrough rates have been lower for the J&J vaccine than the Pfizer and Moderna vaccines during the Omicron surge,” he added.

What We Don’t Know

How big another U.S. uptick could be. While Covid-19 cases, hospitalizations and deaths have been declining across the U.S. in recent weeks, patterns there tend to follow what happens in Europe, where cases have reached record levels in some countries. It’s unclear whether cases in the U.S. will spike in a similar manner or how severe this might be, though waning immunity, the spread of the more infectious BA.2 omicron relative and the removal of almost all pandemic restrictions make some increase likely. “They were never destined to go down forever,” Adalja said. However, experts have told Forbes it is unlikely to hit levels of previous waves due to the new tools available to us and the immunity from vaccination and past infection.