There is now a large body of evidence showing that the approved vaccines for COVID-19 in the United States — those from Pfizer/BioNTech, Moderna, and Johnson & Johnson (Janssen) — are safe and offer substantial protection against the viral infection. But nearly every medical intervention, including vaccines, carries some level of risk for side effects or complications. So far, there is every indication that the most common side effects of COVID-19 vaccines tend to be mild — including soreness at the injection site, tiredness, fever, and chills that tend to go away within a day or two. A more serious concern is a severe allergic reaction within minutes of receiving the vaccine, which is extremely rare but requires immediate medical attention.
Still, many researchers are on the lookout for potential health complications linked to COVID-19 vaccines — especially since the Johnson & Johnson vaccine, in particular, was found to be linked to an extremely rare clotting syndrome in younger people. This finding led the U.S. Food and Drug Administration (FDA) to briefly suspend the vaccine’s emergency use authorization earlier this year while it investigated the clotting risk, and the agency ultimately concluded that the benefits of the vaccine far outweighed the risks.
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Any clotting risk in older adults, though, could be potentially much more serious, since older people are at far greater risk for serious cardiovascular events — like stroke and heart attack — that are linked to clotting. So for the latest analysis, researchers aimed to look at whether older adults who had received a COVID-19 vaccine were any more likely to have a stroke or heart attack than those who hadn’t received a vaccine. They used data fro the French National Health Data System, which included 11,113 hospitalizations for heart attack, 17, 014 hospitalizations for an ischemic stroke, 4,804 hospitalizations for a hemorrhagic stroke, and 7,221 hospitalizations for a pulmonary embolism among adults ages 75 and older during the study period. Among the people hospitalized for these conditions, varying proportions had received at least one vaccine — 58.6% for heart attack, 54.0% for ischemic stroke, 42.7% for hemorrhagic stroke, and 55.3% for pulmonary embolism.
No increased heart attack, stroke risk found with Pfizer/BioNTech vaccine
When the researchers looked specifically at whether hospitalized patients had received a Pfizer/BioNTech COVID-19 vaccine in the previous 14 days — the period in which any increased risk would be likely to occur — they found no significant difference in any of the cardiovascular events linked to receiving a vaccine dose. People who had received a first vaccine dose in the previous 14 days were 3% less likely to have a heart attack, 10% less likely to have an ischemic stroke, 10% less likely to have a hemorrhagic stroke, and 15% less likely to have a pulmonary embolism. Those who had received a second vaccine dose were 4% more likely to have a heart attack, 8% less likely to have an ischemic stroke, 3% less likely to have a hemorrhagic stroke, and 10% more likely to have a pulmonary embolism — showing no discernible pattern of increased or decreased risk following either dose. All of these differences, in fact, were small enough that based on the number of people involved, they could have been explained by chance.
The researchers noted that this study looked only at the potential risks linked to the Pfizer/BioNTech vaccine, and only at older adults. More studies would be needed to identify any increased risk for stroke or heart attack in younger adults, or linked to other COVID-19 vaccines. But for now, there is every indication that getting one of the most common COVID-19 vaccines has no significant impact on the risk for serious cardiovascular events.
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