Delta and boosters...not rocket science.
TLDR; we recommend booster doses for all eligible patients (and probably just about everyone else). For patients who received J&J vaccine, we recommend boosting with Moderna.
Is the Delta variant more dangerous?
Yes, and no. Covid-19 B.1.671.2 (Delta) spreads more quickly, so in that way, it is worrisome and has driven the increase in hospitalizations over the past few months.
However, it is not more likely to cause severe disease or death in those infected (so it is not more dangerous in that regard).
Fortunately, we know that vaccination very effectively prevents severe Covid-19 disease caused by the Delta variant.
Covid Vaccine Boosters: Should I? Which one? What dose?
A large Israeli study found that rates of confirmed Covid-19 and severe illness were substantially lower among those who received a booster (third) dose of the Pfizer vaccine.
On 10/21/21, Pfizer announced results from a Phase III trial of a third dose of vaccine, which demonstrated a relative vaccine efficacy of 95.6% compared to those who did not receive a booster. This is the first randomized trial to demonstrate the value of booster doses. In this trial with 10,000 participants who had completed a two-shot Pfizer regimen, half were randomised to receive a further equal-strength dose of the shot, and half a placebo. Five cases of Covid were registered in patients receiving the booster compared with 109 who were given a placebo.
People more recently vaccinated had a 36-40% lower rate of “breakthrough” infections than those vaccinated longer ago.
This suggests that protection provided by the Moderna vaccine may decline over time in the same way demonstrated for the Pfizer vaccine. The United States Food and Drug Administration (FDA) and Advisory Committee on Immunization Practices (ACIP) recommend booster Moderna doses, and we agree.
When a booster of the Johnson & Johnson COVID-19 vaccine was given six months after the single shot, antibody levels increased nine-fold one week after the booster and continued to climb to 12-fold higher four weeks after the booster.
Which vaccine to use for the booster?
The Centers for Disease Control and Prevention (CDC) and ACIP reviewed data to include that from a recent study and concluded that booster doses need not be the same vaccine as the initial series.
For patients previously vaccinated with the Janssen (J&J) vaccine, the largest benefit (in terms of total IgG and neutralizing antibodies) was with a Moderna booster; a Pfizer booster dose worked well also.
Unfortunately, while this data is helpful, it’s not definitive. The data is presented as the increase in antibody levels, but we don’t know what that means for patients and illness. Ideally, we would have more information about the risk of hospitalization and death (rather than antibody levels).
Will we know more soon?
We will not have more data anytime soon, so for now, we have to make recommendations based on that data available.
The recommended booster dose for Pfizer and J&J vaccines is the same as for the primary series, and we agree.
There was significant discussion about the ideal dose for Moderna boosters. Moderna applied for a low-dose booster (50μg, which is half the dosage of the original series). During this meeting, they (Moderna) implied that there were three reasons for the lower-dosage:
Should be enough protection for a robust response;
Fewer reactions, such as fever and muscle aches, compared to the higher dosage;
Global pressure. By dividing the vaccines in half, there will be more vaccine available for global supply.
These arguments did not convince some committee members; some said a low-dose booster could cost people the potential benefit of a full-strength booster over time and that it might have an impact on durability. The “global pressure” argument is unpersuasive in the United States, where we have wasted as many as 1,000,000 doses of expired vaccine in some months. Given that the mixed booster study used the 100 mcg dose for Moderna boosters, we recommend boosting with the full (100 mcg) dose.
What about the risks?
In the United States, nearly 12M people have received a booster vaccine dose, and via V-safe, we have data on almost 300,000 of them. Vaccine reactions were less frequent following the 3rd dose than following doses 1 or 2.
Thus far, Israel has boosted 3.7 million people, and it’s not any risker than the original series. In fact, in terms of myocarditis, a booster is less risky because of the longer period between doses. Israel reported only 17 cases of myocarditis/pericarditis after the booster. All these cases were among males, all resolved without any long-term effects.
Total reports to VAERS (Vaccine Adverse Events Reporting System) include 2,460 cases of myocarditis among 366M mRNA vaccine doses administered. The risk with Moderna vaccine is slightly higher than that with the Pfizer vaccine, but both are vastly less than that with Covid infection (more than 2%).
A study published 10/22/21 in Morbidity and Mortality Weekly Report (MMWR) found that overall non-Covid mortality was lower among those vaccinated than among those not. So the bottom line here is that there is nothing to suggest that Covid vaccines increase mortality via myocarditis or any other mechanism.
Bottom line, our recommendations:
If your primary vaccine doses were Moderna, we recommend a third dose of the Moderna vaccine at least 6 months after the second dose.
If your primary vaccine doses were Pfizer, we recommend a third dose of either the Pfizer or Moderna vaccine at least 6 months after the second dose.
If your primary vaccine dose was Janssen (J&J), we recommend a booster dose with the Moderna vaccine at least 2 months after the first dose.