Moderna cooperating with investigation into possible COVID-19 vaccine allergic reactions

Moderna said in a statement yesterday that it is ‘fully’ cooperating with an investigation into possible allergic reactions at a vaccination centre in the US administering its mRNA-based COVID-19 vaccine.

The adverse events were reported by the California Department of Public Health (CDPH) in the US, after a number of individuals at a vaccination centre in San Diego were treated for possible allergic reactions following vaccination using doses from one lot of Moderna’s jab.

On Sunday, California’s state epidemiologist Dr Erica Pan issued a statement with recommendations for healthcare providers to pause vaccination from the lot in question – no. 041L20A – after the possible allergic reactions.

"Our goal is to provide the COVID-19 vaccine safely, swiftly and equitably," said Pan.

"A higher-than-usual number of possible allergic reactions were reported with a specific lot of Moderna vaccine administered at one community vaccination clinic. Fewer than ten individuals required medical attention over the span of 24 hours,” she added.

According to the statement, over 330,000 doses from this lot have been distributed to 287 providers across California.

In its own statement, Moderna said that a total of 1,272,200 doses were produced in batch 041L20A, with nearly a million doses already distributed to approximately 1,700 vaccination sites in 37 states in the US.

Moderna, along with the US Centers for Disease Control and Prevention (CDC) and US Food and Drug Administration (FDA) are reviewing the lot in question as well as related medical information.

The CDPH added that no additional clusters of potential serious allergic reactions have been reported and that the risk of a serious adverse reaction is very small.

Moderna’s vaccine received an emergency use authorisation (EUA) from the FDA last month, becoming the second COVID-19 jab to be granted an EUA in the US after Pfizer/BioNTech’s mRNA-based vaccine.

In December 2020, the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) issued guidance warning people with a history of allergic reactions not to get the Pfizer/BioNTech COVID-19 vaccine.

This guidance followed reports of anaphylaxis – severe allergic reactions – and one report of a possible allergic reaction following immunisation with the Pfizer/BioNTech vaccine in the UK.

Anaphylaxis is a very rare side effect with any vaccine, the MHRA said in a statement issued at the time.

“Most people will not get anaphylaxis and the benefits in protecting people against COVID-19 outweigh the risks,” said June Raine, chief executive of the MHRA.