Research on COVID-19 vaccines' duration, reactions, prioritization

Antibodies persisted six months after vaccination, a graded dosing protocol allowed patients with reactions to a first shot to get a second, and surveyed Americans wanted to prioritize front-line workers and those with chronic conditions for vaccination.

Trial participants who received the Moderna vaccine still had antibodies six months after vaccination, reported a letter published by the New England Journal of Medicine on April 6. The report included 33 healthy adults participating in an ongoing phase 1 trial who were tested 180 days after the second dose with three different serological assays. Antibody activity remained high in all age groups, which included some patients over age 70 years. The authors said that monitoring of these antibody responses would continue but that so far “data show antibody persistence and thus support the use of this vaccine in addressing the Covid-19 pandemic.”

A graded dosing protocol was used to fully vaccinate two patients who had allergic reactions to the first dose of the Moderna vaccine, reported a letter published by Annals of Internal Medicine on April 6. Both patients had histories of allergies and developed symptoms (which were treated successfully) within 15 minutes of the shot. After shared decision making, they underwent a graded dosing protocol for the second dose (five shots 15 minutes apart). One had mild allergic symptoms, the other none, and both showed IgG antibodies against SARS-CoV-2 in the weeks after vaccination, leading the authors to conclude that immediate hypersensitivity reactions to the Pfizer-BioNTech and Moderna vaccines should not lead to automatic deferral of the second dose. “Instead, referral to an allergy and immunology physician for further evaluation and management should be considered,” they wrote. An article in the April 2021 ACP Internist offered experts' perspectives on allergies and COVID-19 vaccination.

Data about cases of clots after receipt of the AstraZeneca vaccine were provided in two articles published by the New England Journal of Medicine on April 9. A study described the features of 11 patients who presented with thrombosis five to 16 days after vaccination and findings from blood samples of a total of 28 patients with thrombosis after vaccination. All tested positive for antibodies against platelet factor 4, leading the authors to conclude that the vaccine can, in rare cases, lead to immune thrombotic thrombocytopenia. A brief report described five similar cases and also came to the conclusion that there is a vaccine-related variant of spontaneous heparin-induced thrombocytopenia.

Americans mostly agreed with the vaccine prioritization framework developed by the National Academies of Sciences, Engineering, and Medicine, according to a study published by JAMA Network Open on April 9. Almost 5,000 people were surveyed in September 2020, and most listed health care workers and adults of any age with serious comorbid conditions as high-priority groups for vaccination. Younger people were more likely than older people to prioritize vaccination of healthy adults age 65 years or older. “The results suggest substantial community-mindedness, as more than 80% of respondents were also willing to wait in line behind teachers, grocery store workers, and people in Black, Hispanic, Native American, and other communities that have been disproportionately affected by COVID-19,” the authors said.