Testing began in Britain on Thursday to determine if different COVID-19 vaccines can be used together in a two-shot regimen.Researchers are aiming to inoculate more than 800 volunteers with one shot of the Pfizer-BioNTech vaccine, followed either four or 12 weeks later with a booster shot of the vaccine developed jointly by AstraZeneca and Oxford University, or vice versa.The vaccines were developed with different technology — the Pfizer vaccine through messenger RNA (mRNA), while the AstraZeneca-Oxford vaccine is adenovirus viral vector, or common cold virus.Health officials say if two vaccines developed with different technology are able to be used interchangeably, it could allow greater flexibility in immunization campaigns around the world.In a related development, The Guardian newspaper says an analysis of Israel’s mass vaccination program has found that a single dose of the Pfizer-BioNTech vaccine provides 90% protection against the novel coronavirus by 21 days. Researchers at Britain’s University of East Anglia contradict an earlier study from Israel that suggested one dose may not give adequate protection.Meanwhile, Oxford University says its COVID-19 vaccine is 76% effective at preventing infection for three months after a single dose. The findings were part of the same study released Wednesday that found the vaccine cut transmission of the virus by two-thirds.The study has not been peer-reviewed, but Britain’s Health Secretary Matt Hancock told the BBC the findings are “good news.””It does show the world that the Oxford jab works, it works well,” Hancock said.The vaccine has come under criticism from other nations in Europe in recent days with officials expressing concerns about the lack of data regarding its effectiveness in older people.Preparations for the Australian Open, the first major tennis tournament of 2021, have been thrown into disarray after a worker at a quarantine hotel in Melbourne tested positive for COVID-19. The positive case prompted tournament organizers and local health authorities to order more than 500 players and support staff to isolate in their rooms until they are tested, and several warm-up tournaments that were scheduled for Thursday were canceled.The tournament was already off to a rough start after more than 70 players were placed in a strict 14-day lockdown after at least six people who arrived in Melbourne last month tested positive for COVID-19. The cases were linked to three of 17 charter flights that arrived in the southern city carrying more than 1,000 players and their entourages, plus tournament officials and media.The new COVID-19 case in Melbourne is the first confirmed infection in Victoria state in 28 days. City officials have reimposed an order for masks in indoor public places, as well as limits on the number of people who can gather indoors.Victoria state Premier David Andrews said in spite of the new positive case, the Grand Slam tournament will still begin next Monday as scheduled, but added there were “no guarantees.”
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