Questions have been raised as to why restaurants and pubs that serve food might be closed to control outbreaks of Covid-19, when many outbreaks are in private households, and very few confirmed outbreaks have been linked to settings such as pubs and restaurants.

However, a leading public health expert has said that while the question is understandable, it arises due to a misinterpretation of the data.

In a Twitter thread, Professor Philip Nolan, Chair of the National Public Health Emergency Team's Epidemiological Modelling Advisory Group, said that the idea that very few cases are connected to such social settings "is misreading and misinterpreting the data on outbreaks and clusters".

He explained that contact tracing resources are concentrated on where the virus is likely to spread to, rather than on where it has come from.

Prof Nolan gave the example of someone who contracted the virus in a restaurant, saying it will then have "multiplied silently" inside them for three days before they start "shedding virus, and potentially infecting others" for two days, at which point they may then become symptomatic, self-isolate, and get a test. 

If they test positive, contact tracers will only ask them about the previous 48 hours, when they were potentially infectious, and not the day five days earlier when they contracted the virus in a restaurant.

The individual's contacts will then be tested. If their family members test positive, it becomes a household outbreak.

The original case is classed as community transmission, even though the individual "got it in a restaurant and brought it home".

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Prof Nolan said public health officials would "like to go back and find out where people are getting the virus, but we don't have the time or resources to pursue this academic exercise".

He added that international evidence shows "social settings, including bars and restaurants, drive community transmission".

He said that "sadly, unless we stop mixing in these settings, we know the disease will spiral out of control".  

Professor Nolan acknowledged the hard work of those working in pubs and restaurants to minimise the risks and that their livelihoods are at stake.