COVID-19 vaccination tied to reduced household transmission
COVID-19 transmission among household members may be reduced 40% to 50% when a person has been vaccinated 21 days or more, according to a New England Journal of Medicine letter to the editor yesterday.
The researchers looked at more than 1 million household contacts in England from Jan 4 to Feb 28 and found that both percentages and absolute numbers showed fewer secondary cases when the index patient had received at least one dose of the AstraZeneca/Oxford or the Pfizer/BioNTech COVID-19 vaccine 21 or more days prior. Of the index patients that were vaccinated, the researchers add that 93% hadn’t received their second vaccine dose yet.
By cross-referencing all lab-confirmed COVID-19 cases in England by address and looking at COVID-19 vaccine data, the researchers identified 960,765 unvaccinated household contacts of unvaccinated index patients. Of these, 96,898 contacts developed COVID-19 infection within 14 days (10.1%). In comparison, COVID-19 index patients who had received the AstraZeneca vaccine 21 or more days prior to infection had a total of 3,424 household contacts, of whom only 196 (5.7%) became infected. Pfizer-vaccinated index patients had 5,939 linked household contacts, of whom 371 (6.2%) developed subsequent COVID-19 infections.
“Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) prevents infection and reduces the severity of coronavirus disease 2019 (Covid-19) in vaccinated persons,” the researchers write. “Assessment of infection risks among household contacts according to the timing of vaccination of the index patient showed protective effects when the vaccine had been administered at least 14 days before the positive test.”
Jun 23 N Engl J Med letter
Study: Skin reactions occur in about 2% of mRNA vaccine recipients
A study yesterday in JAMA Dermatology shows that, among 40,000 healthcare employees receiving either the Pfizer or Moderna mRNA vaccines, only 1.9% reported injection-site skin reactions, including itching, rash, and swelling, after their first dose.
“With more than 600 employees with first-dose cutaneous reactions included, 83% did not have recurrent cutaneous reactions. An additional 2.3% reported cutaneous reactions only after the second dose of the vaccine,” the authors said.
The study was based on surveys completed by 40,640 employees of Massachusetts General Hospital (MGH) after the first dose of vaccine. Women were more likely than men to report the adverse reaction (85% of reactions), and White people reported more reactions (62%) compared with minorities (7% Black, 12% Asian).
“This is the first information we have on risk of recurrence of skin reactions after dose 2 when there is a dose 1 reaction. Our findings could provide critical reassurance to people with rashes, hives and swelling after dose 1 of their mRNA vaccines,” said study lead Kimberly G. Blumenthal, MD, MSc, in an MGH press release.
Cutaneous reactions, unlike anaphylaxis, are not a contraindication to revaccination, and referral to a dermatologist or allergist is typically not necessary unless the patient has an immediate or severe reaction, the authors advise.
In another study published in the same journal, authors found a weak correlation between COVID-19 infection and chilblains, small raised red rashes on hands and feet, usually associated with exposure to the cold.
The authors looked at 780 patients with chilblains in Northern California reported during the pandemic, and found only 17 of 456 (3.7%) tested positive for COVID-19, and only 9 of 456 (2.0%) were positive for COVID-19 within 6 weeks of the chilblains diagnosis.
Jun 23 JAMA Dermatol vaccine reactions study
Jun 23 MGH press release
Jun 23 JAMA Dermatol chilblains study