SARS-CoV-2 does not replicate in embryonated hen’s eggs or in MDCK cell lines

The advent of COVID-19, has posed a risk that human respiratory samples containing human influenza viruses may also contain SARS-CoV-2. This potential risk may lead to SARS-CoV-2 contaminating conventional influenza vaccine production platforms as respiratory samples are used to directly inoculate embryonated hen’s eggs and continuous cell lines that are used to isolate and produce influenza vaccines. We investigated the ability of these substrates to propagate SARS-CoV-2 and found that neither could support SARS-CoV-2 replication.

Influenza vaccine production technologies: past, present and future

Influenza is a constantly evolving global health threat that leads to substantial morbidity and mortality particularly in vulnerable populations at either end of the age spectrum. Society has responded by creating a global public-private system that involves constant surveillance, candidate virus generation, and release reagent generation linked to worldwide influenza vaccine manufacturing capabilities. It was initially recognised that influenza circulates as multiple antigenically distinct subtypes, which led to the generation of vaccines containing multiple influenza strains. The first and still current major process used for influenza vaccine production is infection of embryonated hen's eggs with influenza virus. While this approach was a true advancement, some shortcomings such as lack of vaccine match to circulating strains due to egg adaptation and production capacity limitations have led to recent innovations in mammalian cell production and synthetic technologies aimed at further improving global influenza responses.