ITV News Political Correspondent David Wood explains the latest change to England's self-isolation exemption rules
Emergency workers - including police, firefighters and Border Force staff - and some transport workers will be included in the "test to return to work" scheme that was initially launched for food supply workers to avoid staff shortages from the "pingdemic".
The "test to return to work" scheme means those who have received an NHS Covid 19 app alert to self-isolate, or have been called by Test and Trace, will be able to continue working if they test negative for coronavirus.
The scheme applies to everyone and not just those who are double vaccinated.
The government announced that 200 more testing sites will open so frontline police and fire services can be tested daily.
But these testing sites are not expected to open until Monday at the earliest.
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Border Force staff working on the frontline will be able to take tests at Border Force run testing centres.
Testing sites will also be up set up for workers on England's transport network, including rail infrastructure, ports and airports, and haulage firms.
Home Secretary Priti Patel said: "Our brave police officers and fire fighters have shown throughout the pandemic that they have worked tirelessly to keep us safe and serve their communities.
"Border Force have played a vital role in the national effort to keep goods and supplies coming into the country as well as keeping our borders secure.
“Daily testing will keep our frontline teams safe while they continue to serve the public and communities across our country.”
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A "test to return to work" scheme targeting food supply staff was announced on Thursday and involved the promise that up to 500 testing sites would be set up in places like supermarket distribution centres.
The scheme only applies to workers in the food supply sector, for example at supermarket depots and key food manufacturers, but shop staff will not be included in the exemption.
This is despite supermarkets warning earlier this week that the rising number of retail workers being forced to self-isolate was starting to affect the availability of some products, as retail bosses urged shoppers not to stockpile goods.
Under separate rules set out on Thursday, some emergency services workers may be exempt from self-isolation, but they have to test negative for Covid-19 and must be fully vaccinated.
The self-isolation exemption applies to 16 critical sectors, but it is not an automatic exemption for all workers in that sector.
Businesses in these sectors need to contact the relevant government department and tell them which workers they think should be exempt from self-isolation.
The government will then decide whether or not the workers meet the criteria to be exempt.
The criteria is that the person's absence would have a "major detrimental impact on the availability, integrity or delivery of essential services" or a "significant impact on national security, national defence, or the functioning of the state".
The expansion in the "test to return" scheme comes as Boris Johnson faces growing calls to immediately allow fully vaccinated contacts of coronavirus cases to be exempt from isolation if they test negative in order to prevent staffing crises.There are plans to end self-isolation for the double-jabbed and under-18s from August 16 if they test negative for Covid-19.
But businesses, joined by London Mayor Sadiq Khan, are demanding a more immediate end to the “pingdemic” by loosening the isolation rules for everyone who is fully vaccinated.
There is some cross-party support, with former health secretary Jeremy Hunt having warned the government it faces “losing social consent” for isolation if it does not act now.