Coronavirus: What's happening in Canada and around the world on July 30

Scientists in the U.S. who studied a big COVID-19 outbreak in Massachusetts concluded that vaccinated people who got so-called breakthrough infections carried about the same amount of the coronavirus as those who did not get the shots.

Large outbreak in Massachusetts mostly infected vaccinated people, CDC study finds

People are seen in Provincetown, Mass., in May 2020. A study by the U.S. Centers for Disease Control and Prevention about a recent COVID-19 outbreak in Provincetown found that three-quarters of the infections were in fully vaccinated individuals (Maddie Meyer/Getty Images)

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In another dispiriting setback for U.S. efforts to stamp out the coronavirus, scientists who studied a large COVID-19 outbreak in Massachusetts concluded that vaccinated people who got so-called breakthrough infections carried about the same amount of the coronavirus as those who did not get shots.

Health officials on Friday released details of that research, which was key in this week's decision by the Centers for Disease Control and Prevention (CDC) to recommend that vaccinated people return to wearing masks indoors in parts of the U.S. where the delta variant is fuelling infection surges.

The authors said the findings suggest that the CDC's mask guidance should be expanded to include the entire country, even outside of hot spots.

The findings have the potential to upend past thinking about how the disease is spread. Previously, vaccinated people who got infected were thought to have low levels of virus and to be unlikely to pass it to others. But the new data shows that is not the case with the delta variant.

A health worker tends to a COVID-19 patient at a Los Angeles hospital on Friday. (Mario Tama/Getty Images)

The outbreak in Provincetown — a seaside tourist spot on Cape Cod, in the county with Massachusetts's highest vaccination rate — has so far seen more than 900 cases.

The CDC report is based on about 470 COVID-19 cases linked to the Provincetown festivities, which included densely packed indoor and outdoor holiday events at bars, restaurants, guest houses and rental homes.

Researchers ran tests on a portion of them and found roughly the same level of virus in those who were fully vaccinated and those who were not.

Three-quarters of the infections were in fully vaccinated individuals. Among those fully vaccinated, about 80 per cent experienced symptoms with the most common being cough, headache, sore throat, muscle aches and fever.

In the report, the measure researchers used to assess how much virus an infected person is carrying does not indicate whether they are actually transmitting the virus to other people, said Dr. Angela Rasmussen, a virologist at the University of Saskatchewan.

WATCH | 'If you are unvaccinated ... your luck is about to run out,' says U.S. physician: 

'If you are unvaccinated ... your luck is about to run out': physician

1 year ago
Duration 6:56
Dr. Peter Hotez, co-director of vaccine development at Texas Children's Hospital in Houston, emphasized the risks unvaccinated people are running against the delta variant of COVID-19.

CDC officials say more data is coming. They are tracking breakthrough cases as part of much larger studies that involve following tens of thousands of vaccinated and unvaccinated people across the country over time.

Meanwhile, internal documents on breakthrough infections and the delta variant suggest the CDC may be considering other changes in advice on how the nation fights the coronavirus, such as recommending masks for everyone and requiring vaccines for doctors and other health workers.

The delta variant, first detected in India, causes infections that are more contagious than the common cold, flu, smallpox and the Ebola virus, and it is as infectious as chickenpox, according to the documents, which mentioned the Provincetown cases.

The documents, first obtained by The Washington Post, note that COVID-19 vaccines are still highly effective against the delta variant at preventing serious illness and death.

What's happening in Canada

A COVID-19 rapid testing area is seen on the international arrivals level of the Vancouver International Airport in Richmond, B.C., on Friday. (Darryl Dyck/The Canadian Press)
  • Alberta nixing remaining COVID-19 protocols sparks outrage among physicians.
  • Manitoba sends 5,500 doses of AstraZeneca-Oxford vaccine back to Ottawa.

What's happening around the world

As of Friday, more than 196.6 million cases of COVID-19 had been reported worldwide, according to Johns Hopkins University. More than 4.1 million deaths had been reported.

In Asia, Japan on Friday expanded a coronavirus state of emergency to four more areas in addition to Tokyo following record spikes in infections as the capital hosts the Olympics.

WATCH | WHO chief praises handling of COVID-19 risk at Tokyo 2020:

WHO chief praises handling of COVID-19 risk at Tokyo 2020

1 year ago
Duration 0:58
WHO director general Tedros Adhanom Ghebreyesus says Japan and the IOC did their best to minimize the risk posed by COVID-19 at the Tokyo 2020 Olympic Games as new cases soar. Tokyo has reported a record increase for three days in a row.

In the Americas, France is deploying military medics and ICU units to the French Caribbean to relieve hospitals facing a coronavirus surge. Military planes are also bringing some critically ill patients to the French mainland for treatment.

In Africa, Ivory Coast has tripled its daily administration of COVID-19 vaccine doses in three months, the region's World Health Organization chapter says.

In Europe, Germany will require people entering the country to show a negative coronavirus test if they haven't been vaccinated or recently recovered from COVID-19.

With files from CBC News

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