US President Joe Biden looks at his grandson Beau Biden as first lady Jill Biden waves and walks to board Air Force One at Andrews Air Force Base, Md., Aug 10, 2022. (MANUEL BALCE CENETA/AP)

LONDON / WASHINGTON / PRAGUE - US first lady Jill Biden has testified positive for COVID-19, her communications director Elizabeth Alexander said on Tuesday.

US first lady Jill Biden is currently staying at a private residence in South Carolina and will return home after she receives two consecutive negative tests, her spokeswoman said

After testing negative for COVID-19 on Monday during her regular testing cadence, the first lady began to develop cold-like symptoms late in the evening. She tested negative again on a rapid antigen test, but a PCR test came back positive, the spokeswoman said.

Double-vaccinated and twice boosted, Jill Biden is "only experiencing mild symptoms" and has been prescribed a course of Paxlovid, an antiviral therapy produced by Pfizer and given to patients with COVID-19.

The US first lady, the spokeswoman added, will isolate for at least five days.

She is currently staying at a private residence in South Carolina and will return home after she receives two consecutive negative tests.  

President Joe Biden tested negative for COVID-19 on Tuesday, the White House said.

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On Monday, US Secretary of Defense Lloyd Austin also tested positive for COVID-19.

This is the second time that the US defense chief has contracted the coronavirus.

"I am experiencing mild symptoms, and will quarantine at home for the next five days," Austin, 69, said in a statement announcing the latest infection.

US Secretary of Defense Lloyd Austin pauses while speaking during a media briefing at the Pentagon, Nov 17, 2021, in Washington. (ALEX BRANDON / AP)

Austin, who was fully vaccinated and twice boosted, said his last in-person contact with US President Joe Biden was on July 29, and that he "will retain all authorities and plan to maintain my normal work schedule virtually from home."

Austin tested positive for COVID-19 in early January this year.

A child (left) looks at soap bubbles as she waits to receive the anti coronavirus COVID-19 Biontech/Pfizer vaccine for children aged 5-11 in the General University Hospital in Prague, Czech Republic on Dec 21, 2021. (MICHAL CIZEK / AFP)

Czech Republic

The Czech Health Ministry on Monday announced a new campaign to promote COVID-19 vaccination amid concerns for an autumn wave of the pandemic and launched registrations for the second booster dose.

"Adults in the Czech Republic can be revaccinated with a second booster dose at a practitioner's office or without an appointment in a network of vaccination centers as of July 18... Today we are launching a reservation system for this latest dose as well, which will simplify the entire revaccination process for people," Health Minister Vlastimil Valek said in a statement.

The minister also said that the Czech Republic will not re-introduce drastic restrictions aimed at reducing the spread of COVID-19 during the upcoming autumn wave.

Although it is not known precisely when the autumn wave will begin, the Health Ministry hopes to launch the main part of its vaccination campaign under the slogan --"We get vaccinated to live without fear"-- in September, in public media and outdoor advertising.

"As a doctor and as a minister, I appeal to each of you to get vaccinated. Vaccines are tested and proven to reduce the risk of infection and severe cases," he tweeted.

The minister said that vaccination will "probably have to be repeated as long as the virus is with us." He also emphasized the ministry's recommendation of wearing respirators in high-risk areas, like hospitals and nursing homes.

Since COVID-19 was first detected in the Czech Republic in March 2020, there have been a total of 4,012,244 confirmed cases - not including re-infections, as of Sunday, according to Health Ministry data. A total of 40,647 have succumbed to the virus.

Meanwhile, nearly 6.9 million people in the country, which has a population of about 10.5 million, have been fully vaccinated.

Pfizer CEO Albert Bourla poses for pictures during the inauguration ceremony of the company’s new center for Digital Innovation and Business Operations and Services, in Thessaloniki, on Oct 12, 2021. (SAKIS MITROLIDIS / AFP)

Pfizer

Pfizer Chief Executive Officer Albert Bourla said on Monday he had tested positive for COVID-19 and was experiencing very mild symptoms.

Bourla, 60, said he had started a course of the company's oral COVID-19 antiviral treatment, Paxlovid, and was isolating and following all public health precautions.

UK

Britain, the first country to approve a coronavirus vaccine in late 2020, has now also given the first green light to a variant-adapted shot that targets both the original and Omicron version of the virus.

While existing COVID-19 vaccines continue to provide good protection against hospital admissions and death, vaccine effectiveness has taken a hit as the virus has evolved

The UK medicines regulator gave the so-called bivalent vaccine made by US drug company Moderna conditional approval as a booster for adults on Monday.

Later on Monday, the UK's Joint Committee on Vaccination and Immunisation backed the use of the variant-adapted shot in the country's booster campaign starting September.

The MHRA's Moderna decision was based on clinical trial data that showed the booster triggered "a strong immune response" against both Omicron (BA.1) and the original virus, it said.

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Moderna in June said trial data showed that when given as a fourth dose, the variant-adapted shot raised virus-neutralizing antibodies by eight-fold against Omicron.

The MHRA also cited an exploratory analysis in which the shot was found to generate a "good immune response" against the currently dominant Omicron offshoots BA.4 and BA.5.

According to Moderna, trial data showed its variant-adapted booster generated virus-neutralizing antibody levels against the subvariants that were 1.69 times higher than those given the original booster.

According to Moderna, trial data showed its variant-adapted booster generated virus-neutralizing antibody levels against the subvariants that were 1.69 times higher than those given the original booster

However, the correlation between neutralizing antibody levels and vaccine effectiveness against disease - in particular severe disease - remains unclear.

No serious safety concerns were identified with the new Moderna formulation, the MHRA added on Monday.

While existing COVID-19 vaccines continue to provide good protection against hospital admissions and death, vaccine effectiveness has taken a hit as the virus has evolved.

"What this bivalent vaccine gives us is a sharpened tool in our armoury to help protect us against this disease as the virus continues to evolve," MHRA Chief Executive June Raine said in a statement.

However, the virus is unlikely to stand still and Omicron-targeted immunity might push the virus down other evolutionary paths, added Jonathan Ball, professor of molecular virology at the University of Nottingham.

European Medicines Agency officials expect COVID variant-adapted vaccines to be approved in the European Union by September, and have signalled the regulator is open to using shots targeting the older BA.1 variant this autumn, given those specifically targeting newer subvariants are further behind in clinical development.

In contrast, the US Food and Drug Administration has said it will seek the specific inclusion of the newer BA.4 and BA.5 offshoots of Omicron in any new shots used domestically.