Virus World

Anaphylaxis was rarely reported among the first 4 million recipients of the second COVID-19 vaccine authorized for use in the United States, the CDC and FDA reported in MMWR. According to the report, between Dec. 21 and Jan. 10, more than 1,200 adverse events were reported following vaccination with Moderna’s COVID-19 vaccine. Of these, 108 were determined to be allergic reactions and 10  were confirmed as cases of anaphylaxis — equating to 2.5 cases per million doses administered — according to data compiled from the Vaccine Adverse Event Reporting System. The report outlined that nine of the cases of anaphylaxis were reported among people with a documented history of allergies or allergic reactions, including five with a history of anaphylaxis. According to the report, the median time between vaccine receipt to symptom onset was 7.5 minutes but ranged from anywhere between 1 and 45 minutes. Of the eight individuals with follow-up information available, all reportedly recovered or had been discharged home.

“Based on this early monitoring, anaphylaxis after receipt of Moderna COVID-19 vaccine appears to be a rare event; however, comparisons of anaphylaxis risk with that associated with non–COVID-19 vaccines are constrained at this time by the limited data available this early in the COVID-19 vaccination program,” members of the CDC COVID-19 Response Team and the FDA wrote in the report.  Moderna’s vaccine was the second COVID-19 shot authorized for emergency use in the U.S. Earlier this month, the CDC and FDA reported that the first vaccine, developed by Pfizer and BioNTech COVID-19, also was rarely associated with anaphylaxis, with 21 cases of confirmed among the first 1,893,360 recipients of the vaccine. At the time, Nancy E. Messonnier, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases, said the number “may seem high, but this is still a rare outcome.”

As a precaution, researchers said that vaccination sites should be outfitted to handle these reactions should they arise, and the CDC has issued updated interim clinical considerations to reflect that. “Locations administering COVID-19 vaccines should adhere to CDC guidance, including screening recipients for contraindications and precautions, having necessary supplies and staff members available to manage anaphylaxis, implementing recommended postvaccination observation periods, and immediately treating suspected anaphylaxis with intramuscular epinephrine injection,” the authors of the new report wrote.

LONDON (AP) — Britain’s medical regulator warned Wednesday that people with a history of serious allergic reactions shouldn’t receive the COVID-19 vaccine from Pfizer and BioNTech as investigators look into whether two reactions on the first day of the country’s vaccination program were linked to the shot. Professor Stephen Powis, medical director for National Health Service in England, said the advice was issued on a “precautionary basis” and that the people who had reactions had recovered. Pfizer and BioNTech said they were working with investigators “to better understand each case and its causes.″

In the meantime, the Medical and Healthcare Products Regulatory Agency has said people should not received the vaccine if they have had a significant allergic reaction to a vaccine, medicine or food, such as those who have been told to carry an adrenaline shot — such as an EpiPen — or others who have had potentially fatal allergic reactions. The medical regulator also said vaccinations should be carried out only in facilities that have resuscitation equipment. Such advice isn’t uncommon; several vaccines already on the market carry warnings about allergic reactions, and doctors know to watch for them when people who’ve had reactions to drugs or vaccines in the past are given new products. The two people who reported reactions were NHS staff members who had a history of significant allergies and carried adrenaline shots. Both had serious reactions, but recovered after treatment, the NHS said. Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said the regulator had done the right thing, but the general public shouldn’t be worried about getting the vaccine....

California’s top epidemiologist is warning health providers to delay using a batch of the Moderna COVID-19 vaccine after a “higher-than-usual number of possible allergic reactions” were reported at a Southern Calfiornia vaccination clinic. The affected lot includes 330,000 doses — roughly 1/10th of what the state so far has distributed.  The reaction was observed in fewer than 10 people who required medical attention after receiving the vaccine at one clinic, state epidemiologist Dr. Erica S. Pan said in a statement Sunday night. The conditions of those affected were not released, but health officials described the allergic reaction as “severe.”

The clinic is located in San Diego, the California Department of Public Health reported later. “Out of an abundance of caution and also recognizing the extremely limited supply of vaccine,” read the statement, “we are recommending that providers use other available vaccine inventory and pause the administration of vaccines from Moderna Lot 041L20A until the investigation by the CDC, FDA, Moderna and the state is complete.”  More than 330,000 doses from the affected lot — which arrived in California between Jan. 5 and Jan. 12 — have been distributed to 287 providers across the state, officials said. No other adverse reactions have been reported from that specific lot. “There are not immediate replacement doses during the pause in addition to pending orders scheduled for shipment in the next few days,” public health officials said in the statement sent to health providers. The health department said they would have more information later this week.

Michael Williams is a San Francisco Chronicle staff writer. Email: michael.williams@sfchronicle.com