Study: No risk of serious adverse events in elderly COVID vaccine recipients

A new nationwide study in France involving people 75 years or older found no increase in acute myocardial infarction, stroke, or pulmonary embolism 14 days following each Pfizer-BioNTech COVID-19 vaccine dose. The data was published as a research letter yesterday in JAMA.

To estimate the risk of acute myocardial infarction, hemorrhagic stroke, ischemic stroke, or pulmonary embolism in this age-group, researchers looked at unvaccinated and vaccinated adults 75 or older admitted to the hospital with these conditions between Dec 15, 2020, and Apr 30, 2021, throughout France.

The authors found that over the observation period, 11,113 persons 75 years or older were hospitalized for an acute myocardial infarction, 17,014 for an ischemic stroke, 4,804 for a hemorrhagic stroke, and 7,221 for pulmonary embolism, of whom 58.6%, 54.0%, 42.7%, and 55.3%, respectively, received at least 1 dose of the Pfizer vaccine.

“In the 14 days following either dose, no significant increased risk was found for any outcome,” the authors wrote. “No significant increase for any of the cardiovascular events was observed in the 2 subdivided exposure intervals (1-7 days and 8-14 days).”

The relative incidence of myocardial infarction for the first dose was 0.97 (95% confidence interval [CI], 0.88 to 1.06) and for the second dose, it was 1.04 (95% CI, 0.93 to 1.16); for ischemic stroke for the first dose, 0.90 (95% CI, 0.84 to 0.98) and for the second dose, 0.92 (95% CI, 0.84 to 1.02); for hemorrhagic stroke for the first dose, 0.90 (95% CI, 0.78 to 1.04) and for the second dose, 0.97 (95% CI, 0.81 to 1.15); and for pulmonary embolism for the first dose, 0.85 (95% CI, 0.75 to 0.96) and the second dose, 1.10 (95% CI, 0.95 to 1.26).

The authors said the risk of serious cardiovascular events related to the Pfizer vaccine is not significantly increased for elderly recipients.
Nov 22 JAMA study


Blood clots a risk in COVID-19 patients after hospital stay, data show

A study of 2,832 hospitalized adult COVID-19 patients in Michigan shows that those with a history of blood clots and high concentrations of the biomarkers D-dimer and C-reactive protein were more likely than others to have potentially serious blood clots after release from the hospital.

COVID-19 can induce blood clots in the veins and arteries, the authors noted. A clot can break off and travel to the lungs (pulmonary thromboembolism), where it can stop blood from flowing to the lungs and lead to death.

In the study, published yesterday in JAMA Network Open, a team led by Henry Ford Health System researchers followed COVID-19 patients enrolled at five Detroit hospitals from Mar 1 to Nov 30, 2020. Average patient age was 63.4 years, and 47.6% were men.

Of the 2,832 patients, 36 (1.3%) had venous thrombosis, or blood clots in the veins, after release from the hospital, including 18 with deep vein thrombosis and 2 with thrombosis in the portal vein, the blood vessel that takes blood from the intestines to the liver.

Fifteen cases of thrombosis in the arteries occurred, including 14 instances of acute coronary syndrome (conditions tied to sudden reduced blood flow to the heart) and one transient ischemic attack (“mini stroke”).

Risk factors for post-release venous thrombosis included history of venous thrombosis (odds ratio [OR], 3.24), peak D-dimer (indicating blood clots) concentration greater than 3 micrograms per milliliter (μg/mL) (OR, 3.76), and C-reactive protein level higher than 10 milligrams per deciliter (mg/dl) in the hospital (OR, 3.02). Prescriptions for anticoagulants (drugs to prevent blood clots) at hospital release were linked to a lower incidence of venous thrombosis (OR, 0.18).

The risk of venous thrombosis lessened with time, with a median time to event of 16 days. In contrast, the risk of arterial thrombosis did not wane over time, with a median time to event of 37 days.

“Although extended thromboprophylaxis in unselected patients with COVID-19 is not supported, these findings suggest that postdischarge anticoagulation may be considered for high-risk patients who have a history of venous thromboembolism, peak D-dimer level greater than 3 μg/mL, and predischarge C-reactive protein level greater than 10 mg/dL, if their bleeding risk is low,” the authors concluded.
Nov 22 JAMA Netw Open study

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