COVID-19 Vaccines: AstraZeneca on Blood Clots / Second-Dose Delivery / Skilled Nursing Facilities

AstraZeneca on blood clots: AstraZeneca issued a statement on Sunday to reassure the public about the safety of its COVID-19 vaccine after several European Union countries halted its use over concerns about blood clots. The company noted that among more than 17 million people who’ve received the vaccine in the E.U. and U.K., 15 cases of deep venous thrombosis and 22 of pulmonary embolism were reported through March 8. “This is much lower than would be expected to occur naturally in a general population of this size and is similar across other licensed COVID-19 vaccines,” the company said. It also noted that in clinical trials, thrombotic events occurred less often in the vaccine than placebo group. AstraZeneca said it “is keeping this issue under close review but available evidence does not confirm that the vaccine is the cause.”

Second-dose delivery: Among nearly 12.5 million Americans who received their first dose of COVID-19 mRNA vaccine between mid-December and mid-February and for whom enough time had passed to receive their second dose, 88% received their second dose, nearly 9% hadn’t received their second dose but were still within the allowable time frame to do so (i.e., within 42 days), and over 3% missed their second dose (i.e., were no longer within the allowable time frame), according to a CDC analysis in MMWR. American Indian/Alaska Natives and people aged 16 to 44 years were more likely than others to miss their second dose. The researchers emphasize several strategies to help ensure that second doses are delivered as recommended, such as scheduling the second dose at the first-dose visit and sending multiple reminders to patients.

Skilled nursing facilities: Partial COVID-19 vaccination with the Pfizer-BioNTech vaccine was 63% effective at preventing SARS-CoV-2 infection, including asymptomatic and symptomatic cases, during large outbreaks at two Connecticut skilled nursing facilities, researchers report in MMWR. Partial vaccination was defined as more than 14 days after the first dose through 7 days after the second. (There were neither enough cases nor enough follow-up time after the second dose to assess the effectiveness of full vaccination.) The researchers conclude that in this high-risk population, which was excluded from preauthorization clinical trials, the first vaccine dose seems as effective as in the general adult population. They emphasize, however, the importance of completing the two-dose vaccine series.

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Créditos: Comité científico Covid