Breakthrough infections are on the rise, including multi-person outbreaks among the vaccinated. These infections are very concerning. Since I am nearly 80, in good health, and have been fully vaccinated (Pfizer-BioNTech) since January 2021, I have a personal, if biased, stake in the decision to offer boosters. My vote is for a booster campaign. Here is why.
The data from Pfizer’s 40,000+ volunteer phase 3 clinical trial begun a year ago and reported to the FDA in December showed a 95% efficacy to prevent severe infection, including hospitalization and death. The vaccine was equally effective at all ages. The results, published in the New England Journal of Medicine, were beyond even the most optimistic hopes when the trial began.
A home run for sure and, with an excellent safety record, more than enough for the FDA to grant emergency use authorization in mid-December 2020. The results were similar for the Moderna vaccine, which was authorized just a few weeks later. The Johnson & Johnson vaccine was authorized in February 2021.
When the Pfizer data was submitted, the longest any volunteer had been vaccinated was a few months. In April 2021, Pfizer reported that antibody levels had declined among the volunteers, and efficacy then stood at about 91%, still excellent.
Antibody levels, especially neutralizing antibody concentrations in the blood, appear to be critical to vaccine efficacy. The half-life of neutralizing antibody is about two months. Therefore, that model predicts that after about 250 days after vaccination, the antibody level will be significantly less able to prevent infection but still sufficient to prevent severe illness and death.
Older people have shown good protection so far, despite their initial lower antibody levels after vaccination(see image above) compared to younger individuals. Among the unvaccinated, older individuals who develop Covid-19 are at much greater risk of an adverse outcome than a younger person. Since antibody levels decline over time, older vaccinated individuals starting with a lower antibody level might be expected to be at higher risk sooner.
Breakthrough infections among vaccinated people are relatively rare, but they seem to be increasing in frequency. An exposed person may develop an infection, and it will probably be asymptomatic or “relatively mild.” But even so-called mild infections can cause loss of work, fatigue, cough that lasts for a few days to a few weeks. Some symptoms have been reported to last at least six weeks, perhaps longer. For an older person, especially those with multiple chronic conditions, even a “mild” infection can be debilitating. And some do proceed to hospitalization and death.
What has become strikingly clear in recent days and weeks is that the vaccinated can readily become infected, especially to the Delta variant, when exposed to an infected person, whether that person has been vaccinated or not. For example, multiple events were held during the July 4th weekend and beyond in and near Provincetown, Cape Cod (Barnstable, County.)
Within some days, 469 Covid-19 infections were identified (image above)among people who had traveled to that area between July 3 and 17, 2021. 74% were fully vaccinated. The Delta variant caused approximately 90% of these infections. Both vaccinated and unvaccinated had similar virus concentrations in their nose samples. Five patients were hospitalized; to date, there have been no deaths.
Dr. Allan Massie, a Johns Hopkins Covid-19 epidemiologist, went to a party in Maryland with 14 friends. All were fully vaccinated, so they wore no masks, consistent with CDC guidelines. Within a few days, 11 developed Covid-19. He published his experience, noting that he had fever, chills, muscle aches, and been weak enough that “I can hardly get out of bed. I don’t wish this on anybody.”
The Israeli government, in collaboration with Pfizer, conducted one of the most effective vaccination campaigns of any country beginning in January 2021. Within a few months, 80+% of the eligible population was vaccinated.
In late July, a study at Hebrew University reported that vaccine efficacy to prevent serious infections had dropped to 80%, still good but not as good as before. Most infections were due to the Delta variant. And a short time later, another study indicated that those who were vaccinated first (e.g., January and February) were more likely to develop a breakthrough infection, usually with the Delta variant, compared to those vaccinated later in the spring. To be fair, it is possible that those vaccinated early had more underlying diseases that predispose to serious covid-19 infections, creating a bias.
Nevertheless, this information was sufficient for the Israeli government to offer, as of July 29th, a booster dose to those over 60 who were vaccinated five or more months before.
Will this make a difference in preventing severe infections? Logic says “Yes,” and Pfizer plans to request authorization for a booster shot in the United States during August. Moderna will follow suit, as will Johnson & Johnson.
When the CEO of Pfizer announced a few weeks ago that he believed boosters would be necessary, much of the media was cynical, noting that Pfizer is a for profit company and just wanted to sell more doses. This was an often “reflex” reaction against capitalism. It is unfortunate because it was Pfizer, like the other vaccine developers, that committed huge sums to rapidly develop these incredible vaccines.
Germany, France, and Britain plan to offer booster shots for older and immune-compromised individuals beginning shortly. The US government is considering them but has not reached a decision, at least not publicly. However, news reports on August 9th suggested that a decision to offer boosters to the immunocompromised was “imminent.” The US has purchased an additional 200 million doses from Pfizer to be allocated to children under 12 years old, if authorized, and for potential boosters.
Government officials remind us that the vaccines are still generally effective in preventing hospitalization and death. That is undoubtedly true but not sufficiently soothing if a booster would help both prevent infection and its “mild” symptoms and, importantly, concurrently reduce transmission. As the Hopkins epidemiologist noted, even mild infections can be debilitating. And as other reports documented, some people with breakthrough infections can have persistent symptoms for more than six weeks.
These multi-person breakthrough infections among the vaccinated are concerning. They seem to be a relatively new occurrence. Indoor masking by all, regardless of vaccine status, will help. Getting more Americans vaccinated will help. And providing boosters, at least to the more vulnerable vaccinated, will help. Until the spread of the virus is curtailed, everyone is at risk. It is time for boosters to begin. The US has or will have plenty of available doses for all who desire them.
Of course, there is the legitimate issue of vaccine equity. Billions of people around the globe have not been vaccinated. They need to be, not only for their own sake but to help prevent the development of another more lethal variant. America has purchased 500 million doses of the Pfizer-BioNTech vaccine and placed orders for other companies’ vaccines for worldwide distribution.
Other developed countries have likewise purchased vaccines for widespread distribution. More purchases will be needed. Until we are “all safe, no one is safe.” The World Health Organization director has implored developed country governments to forgo boosters in favor of sending more vaccines abroad. So far, government responses have been to both offer boosters and ship doses concurrently.
I think these are two separate issues. The relatively few shots used for boosters would not make a sizeable dent in the world’s supply. But it will help Americans stay safe, reduce transmission and limit the opportunity for another variant to develop right here at home.
Said differently, worldwide vaccination is not a zero-sum game. Let’s not penalize those who did the right thing and got vaccinated as soon as it was available here in the United States. Meanwhile, it is also in our best interests to purchase and distribute as many vaccine doses as can be manufactured over the coming years and distribute them to countries in need. It will be money well spent.
Yes, I am biased, but boosters make sense and the time to start is now.
