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expert reaction to press release from PHE on norovirus outbreaks increasing in England

The press release from Public Health England (PHE) provides some simple actions that the public can take in order to reduce the spread of norovirus.


Dr Kathleen O’Reilly, Assistant Professor at the London School of Hygiene and Tropical Medicine (LSHTM), said:

“The Public Health England (PHE) report shows that outbreaks of norovirus in England are increasing in recent weeks. The data show a marked increase in reports within the last month, and the location of these outbreaks include education and (to a lesser extent) care homes. While the outbreaks are not yet as frequent as typically experienced this time of a ‘normal year’, and certainly not high as a typical winter, it does indicate a changing trend.

“Since the COVID-19 pandemic, norovirus cases, along with many other transmissible infectious diseases have remained very low in the community. This has likely been a combination of reduced interaction with others, but also increased hand washing, and staying away from others when feeling ill. With the release of COVID-19 restrictions, it has been expected for some time that transmissible diseases will return as contact rates increase in the community. For example, the increase in norovirus was mentioned in a recent Academy of Medical Sciences report, where it was commented that government and public health agencies need to consider the impact of increasing norovirus on NHS capacity. As part of a Wellcome Trust funded consortium (“Noropatrol”) which aims to understand how best to control norovirus, I have been looking at the potential impact of changing contact patterns and the build-up of population susceptibility on norovirus incidence. Using a mathematical model of norovirus and contact patterns from England collected throughout the COVID-19 pandemic, we identified that norovirus incidence is likely to have started increasing since the re-opening of schools, and that population susceptibility has increased while COVID-19 restrictions have been in place (reference below). The build-up of susceptibility means that an increase in norovirus cases in the summer are quite likely, as we see in this PHE report. The future number of cases in the community will be heavily influenced by contact patterns and steps taken to prevent further spread. In my own work I explored a number of different scenarios (as our understanding of norovirus is less certain than other pathogens), and future cases varied considerably, but could be up to twice as high as a typical year. It should be noted that this work is not yet peer-reviewed but is available on medrvix.

“So what does the report and my research mean? Norovirus cases are increasing, and this is something to be aware of. A typical case of norovirus results in vomiting and diarrhoea, which from personal experience is quite unpleasant, but passes in a couple of days. For people who are immunocompromised or elderly, symptoms may require further support such as hospitalisation, and at a time where hospitals have considerable waiting lists, this increase will likely be a concern for the NHS. However, simple actions will go a long way to prevent norovirus. Washing hands with soap regularly, especially after using the bathroom and prior to meal preparation is really important. If people experience the classic symptoms of norovirus they should not return to work or send children to school until 48 hours have passed. These precautions and others found on the NHS website will go a long way in managing this endemic disease.”

  1. Kathleen M O’Reilly, Frank Sandman, David Allen, Christopher I Jarvis, Amy Gimma, Amy Douglas, Lesley Larkin, Kerry LM Wong, Marc Baguelin, Ralph S Baric, Lisa C Lindesmith, Richard A Goldstein, Judith Breuer, W John Edmunds “Predicted Norovirus Resurgence in 2021-2022 Due to the Relaxation of Nonpharmaceutical Interventions Associated with COVID-19 Restrictions in England: A Mathematical Modelling Study” Medrxiv.



Prof Paul Hunter, Professor in Medicine, The Norwich School of Medicine, University of East Anglia, said:

“In many ways the epidemiology of Norovirus is similar to that of COVID. It is a human pathogen that spreads from one person to another either directly or indirectly. Mostly it is spread by the faecal oral route or via droplets. It can also be foodborne. Norovirus predominantly causes acute vomiting which lasts for about 24 to 72 hours. A proportion of infections are asymptomatic. Also like COVID it has a relatively short period of immunity, and reinfections do occur. It also has a number of different variants, though generally in any given year one variant tends to dominate. Like many of the respiratory viruses it pretty much disappeared within days of the implementation of the first lockdown.

“Pre-COVID, in most years Norovirus caused a large number of outbreaks most notably in hospitals and care homes for older people though outbreaks have been reported from many different settings including hotels, cruise ships and restaurants. Outbreaks in schools did occur but were relatively few in number.

“From today’s report cases have been increasing for about 3 months and are now more frequent than on average before COVID. It is most common in educational settings which mirrors the experience in Australia when they eased COVID restrictions.

“The increase of cases of Norovirus in children almost certainly reflects the reduced immunity to this infection as a result of not being exposed to infection during the past 18 months. We have already started to see cases rising for some of the other respiratory viruses and this reminds us that as we come out of lockdown we are likely to start seeing many other infections rising that may cause problems for public health and the NHS. Doctors in new Zealand have coined the phrase “immunity debt” to describe this phenomenon whereby protection against infection for several months leads to increased problems with otherwise endemic diseases when restrictions are eased. As yet we do not know how much of an additional burden this will cause for public health in the UK but we need to monitor this.”



All our previous output on this subject can be seen at this weblink:



Declared interests

Dr Kathleen O’Reilly: “I am a scientist working on norovirus and (partially) funded by the Wellcome Trust.”

None others received.

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