MIT Medical answers your COVID-19 questions. Got a question about COVID-19? Send it to us at CovidQ@mit.edu, and we’ll do our best to provide an answer.
MIT Medical previously said that we should get any COVID-19 vaccine that is available to us. But after the safety concerns related to the J&J vaccine, I wonder if your advice has changed. Do you still believe that, as you put it, “the best COVID-19 vaccine is the one that you can get?”
We do! Our advice has not changed, and we’ll tell you why.
Let’s begin by talking a little bit about vaccine safety in general, and the Johnson & Johnson (J&J) vaccine, in particular.
The J&J vaccine was authorized for emergency use in the U.S. in February. Its use was paused on April 13 after six reports of serious blood clots with low platelets — a condition called thrombosis with thrombocytopenia syndrome (TTS) — occurring in the first two weeks after vaccination, primarily in younger women. At that point, more than six million doses had been administered in the U.S.
Ten days later, following an extensive safety review, the U.S. Food and Drug Administration and the U.S. Centers for Disease Control and Prevention CDC issued a joint statement allowing use of the vaccine to resume. An exhaustive review of J&J data in the Vaccine Adverse Event Reporting System (VAERS) eventually identified 17 cases of TTS in J&J vaccine recipients, but CDC researchers concluded that 97 percent of reported reactions to the J&J vaccine were “nonserious, consistent with preauthorization clinical trials data.” While the J&J vaccine fact sheet has been revised to include a warning about the risk of TTS, the risk is miniscule —1.9 cases per million in the general population, or, for women younger than 50, seven cases per million.
For Medical Director Cecilia Stuopis, the episode demonstrates a safety-monitoring system working exactly as it should. “A side effect too rare to have appeared even in extensive clinical trials was quickly detected and thoroughly investigated,” she notes. “It’s exactly what VAERS was set up to do.”
If you’ve ever heard that rapid-fire, disembodied voice rattling off potential side effects at the end of a television drug ad, you know that all medications and vaccines have risks. But this fact was largely ignored in reports of rare side effects related to COVID-19 vaccination. For example, as the first COVID-19 vaccines were rolled out in December and January, the news cycle was dominated by reports of several individuals who experienced severe allergic reactions, known as anaphylaxis. It’s a risk that was eventually calculated as 2.5 cases/million for Moderna and 4.7/million for Pfizer. What’s rarely mentioned is that anaphylaxis is a possible side effect of every other vaccine you might ever get. For the seasonal flu vaccine, the anaphylaxis rate is 1.35/million. It’s 2.5/million for the pneumonia (pneumococcal polysaccharide) vaccine and 9.60/million for the shingles (herpes zoster) shot.
Noting that the risk of blood clots is 1 in 5 for hospitalized patients with COVID-19 and 1 in 3,000 for oral contraceptives, Virologist Angela Rasmussen of Georgetown University’s Center for Global Health Science and Security and the Vaccine and Infectious Disease Organization tweeted: “As someone who got the J&J vaccine 8 days ago and who took oral contraceptives for 20 years, I’ll take these odds.”
While Stuopis notes that Rasmussen’s comments lack some context — “We’re talking about different kinds of blood clots here,” she says — she agrees with her larger point. “Drugs and vaccines get approved, and are allowed to remain in use, when it’s determined that the benefits outweigh the risks,” she explains. “And in this case, it’s clear that the risk of a serious reaction to any one of the COVID-19 vaccines — a little more than 50 cases per million doses — is small compared with the risk of the illness itself.”
All three vaccines offer close to 100 percent protection against hospitalization and death. Extensive clinical trials demonstrated the safety of all three vaccines in individuals of different ages and ethnicities. Of note, compared to the Moderna and Pfizer clinical trials, the J&J vaccine was tested on more people who identified as Hispanic/Latino, Black, or African American. The J&J trials also included more people over 60 and more people with chronic health conditions that would put them at higher risk for complications of COVID-19.
Pain and soreness at the injection site, and flu-like symptoms, such as headache, fatigue, fever, and muscle aches, are common side effects of all three vaccines. Symptoms of TTS, on the other hand, may include shortness of breath, chest pain, leg swelling, persistent abdominal pain, severe or persistent headache, blurred vision, and/or bruising or tiny blood spots under the skin beyond the injection site. “Individuals who experience any of these symptoms within three weeks of getting the J&J vaccine should seek medical evaluation,” Stuopis says.
MIT Medical continues to recommend all three vaccines, but you’re likely to have some choice as vaccine availability increases. While the risk of serious side effects is low with all of the currently approved vaccines, women younger than 50, who are at somewhat increased risk of TTS with the J&J vaccine, may want to opt for one of the other two. “On the other hand,” Stuopis adds, “the J&J has the advantage of being a one-dose shot. One and done! No need to make a second appointment and go back for a second shot.”
Bottom line? The best vaccine is still the vaccine you can get. Whether you choose one shot or two, you’re making the safe choice — to protect your own health and the health of your loved ones, friends, and community.