Public Health England (PHE) has issued a warning after norovirus cases were seen to be returning to pre-pandemic levels.

In the past five weeks, 154 outbreaks have been reported, compared to an average of 53 over the same period in the previous five years. The figure is far more than would be expected in summer months across all age groups and settings in England.

Early year educational settings such as nursery and childcare facilities are particularly affected by the rise from the end of May to July.

A similar trend was observed in childcare facilities in New South Wales, Australia. Hand sanitizers are effective against reducing COVID-19 but have little impact on the spread of norovirus.

One outbreak was caused by eating oysters contaminated with norovirus. At least 100 people fell ill in the United Kingdom and 12 in Hong Kong from raw oysters produced by Whitstable Oyster Company in the UK.

The overall number of laboratory confirmed norovirus reports in all age groups has gone back to levels seen in previous years before the coronavirus pandemic.

Potential increase as restrictions ease
It is possible that out of season increases could be seen in the coming months following further easing of COVID-19 control measures, according to PHE. The agency said it would continue to monitor surveillance data to ensure early detection of unusual norovirus activity and outbreaks.

Professor Saheer Gharbia, deputy director of the National Infection Service at PHE, said: “Norovirus, commonly known as the winter vomiting bug, has been at lower levels than normal throughout the pandemic with less opportunity to spread between people in the community but as restrictions have eased we have seen an increase in cases across all age groups.

“Stay at home if you are experiencing norovirus symptoms and do not return to work or send children to school or nursery until 48 hours after symptoms have cleared. As with COVID-19, handwashing is really important to help stop the spread of this bug, but remember, unlike for COVID-19 alcohol gels do not kill off norovirus so soap and water is best.”

The rise in England doesn’t seem to be reflected in Scotland. Public Health Scotland data shows 35 laboratory reports for norovirus up to the week ending July 11 this year. In 2020, the agency received 197 lab reports up to the week ending July 4. The five-year average for the same period between 2015 and 2019 was 855.

Ill people should avoid cooking and helping prepare meals for others until 48 hours after symptoms have stopped, as norovirus can be spread through food contaminated by the virus when food is handled by symptomatic people or infected individuals.

Norovirus can contaminate food and water and can also spread through contact with the feces, vomit of an infected person or contaminated surfaces. It usually involves short-lived vomiting and diarrhea and most people get better without medical treatment.