Do restrictions on travel work against Covid?

The UK authorities is considering whether to present Covid restrictions connected visitors from China, according to Defence Secretary Ben Wallace.

Several countries - including the US, Japan, Italy and Malaysia - are present enforcing investigating connected visitors from China.

This follows a surge successful cases successful China aft Beijing's determination efficaciously to extremity its zero-Covid policy.

But bash specified restrictions work?

Australia imposed immoderate of the strictest question restrictions. From 2020, it closed its borders to non-residents and banned Australians from travelling overseas (with a fewer exceptions).

Countries specified arsenic the UK were much lenient. They required planetary arrivals to usage quarantine hotels and instrumentality Covid tests.

After the pandemic began successful 2020, the World Health Organization (WHO) stated it didn't mostly enactment question bans, arsenic they were "usually not effective".

It said: "Travel measures that importantly interfere with planetary postulation whitethorn lone beryllium justified astatine the opening of an outbreak, arsenic they whitethorn let countries to summation time."

"They tin adversely interaction planetary wellness efforts... by dis-incentivising countries to study and stock epidemiological and sequencing data," it said.

The WHO's director wide said helium was "very acrophobic implicit the evolving concern successful China, with expanding reports of terrible disease".

He said that the WHO needed much elaborate accusation to recognize the risks created by the concern connected the crushed successful China.

And connected Twitter he added: "In the lack of broad accusation from China, it is understandable that countries astir the satellite are acting successful ways that they judge whitethorn support their populations."

Professor Andrew Pollard, manager of the Oxford Vaccine Group told BBC News: "Trying to prohibition a microorganism by adjusting what we bash with question has already been shown not to enactment precise well.

"We've seen that with the bans connected question from assorted countries during the pandemic, that hasn't stopped those viruses travelling astir the satellite eventually."

The connection "eventually" is important here, due to the fact that studies suggest that question restrictions thin lone to hold the dispersed of the microorganism spreading successful a country, but cannot support it retired completely.

One of its authors, Dr Karen Grepin from Hong Kong University, told Reality Check: "We person learned during the pandemic that cosmopolitan measures, applying to each travellers not conscionable those from definite countries, are much effectual than targeted measures, for illustration against Chinese travellers.

"The lone benignant of question restrictions that person been shown to beryllium effectual during the pandemic are those that impact lengthy quarantine periods and I don't deliberation determination is simply a batch of appetite for specified measures astatine this point."

A survey by the WZB Berlin Social Science Center successful Germany looking astatine question restrictions and decease rates successful much than 180 countries reached akin conclusions and added:

Another idiosyncratic advising the UK government, Prof Mark Woolhouse, told Reality Check that restricting arrivals from China to the UK would not bash overmuch to bounds the fig of Covid cases successful this country.

"We person acold excessively galore Covid-19 cases present successful the UK astatine contiguous for imported cases to marque a important contribution," helium said.

It has besides been suggested that restrictions would forestall imaginable caller variants of Covid reaching the UK.

However, if determination is specified a variant, said Prof Woolhouse, question restrictions would beryllium excessively late.

"It volition astir surely person got present already," helium said,

"Measures could lone enactment if the variant happens to look during the play the measures are successful spot and adjacent past they volition lone delay, not prevent, the accomplishment of the variant."

Besides, a caller variant is not much apt to travel successful from China than from anyplace other successful the world.

"Though China is intelligibly experiencing a important question determination is nary crushed to fishy that question volition beryllium a crucible for the emergence of caller variants," said Prof Woolhouse.

"The adjacent variant is astatine slightest arsenic apt to look from determination wholly antithetic - determination are presently astir 4 cardinal reported cases per week worldwide (and surely acold larger numbers are unreported). So wherefore ore lone connected China?"

However, the WHO has said it is acrophobic that China is not sharing accusation astir its latest Covid surge, perchance including the emergence of immoderate caller variants.

"Targeted borderline measures against China whitethorn beryllium much of a governmental connection successful effect to deficiency of information-sharing than a sincere effort to beforehand nationalist health," said Catherine Worsnop from the University of Maryland's School of Public Policy.