The number of major Australian cities heading into lockdown due to the growing presence of the highly infectious delta variant of COVID-19 has risen to four. Authorities in the eastern state of Queensland imposed a three-day lockdown for the capital, Brisbane, and other neighboring regions that took effect Tuesday evening, while in Western Australian state, the capital Perth entered a four-day lockdown. The cities of Darwin, the capital of Northern Territory state, and Sydney in New South Wales state are already under lengthy lockdowns.   At least 150 newly confirmed coronavirus cases across Australia have been traced to a Sydney airport limousine driver who had been transporting international air crews. A transit worker is seen wearing a face mask inside a mostly empty city center train station during a lockdown in Sydney, Australia, June 29, 2021.Australia has been largely successful in containing the spread of COVID-19 due to aggressive lockdown efforts, posting just 30,560 total confirmed cases and 910 deaths, according to Johns Hopkins Coronavirus Resource Center.  But it has proved vulnerable to fresh outbreaks due to a slow rollout of its vaccination campaign and confusing requirements involving the two-shot AstraZeneca vaccine, which is the dominant vaccine in its stockpile. Health officials are now offering the AstraZeneca vaccine to all adults under 60 years of age, lifting a restriction imposed due to concerns of a rare blood clotting condition that has been blamed for at least one death.  Adults under the age of 60 had only been able to receive the two-shot Pfizer vaccine, which is in far less supply than the AstraZeneca shot. Delta variant gains ground The delta variant of COVID-19, which was first detected in India, has now been identified in more than 80 countries and continues to spread rapidly across the globe.  FILE – Pedestrians walk past a sign warning members of the public about a “Coronavirus variant of concern,” in Hounslow, west London, Britain, June 1, 2021.Portugal, Spain and Hong Kong have announced new restrictions on travelers from Britain, where nearly 95% of its COVID-19 cases are of the delta variant.  The United States on Monday raised its travel advisories to Liberia, Uganda, Mozambique and Zambia and United Arab Emirates to Level 4 — “Do not travel” — due to their increasing rates of COVID-19 infections. Bangladesh is preparing to impose a strict one-week lockdown due to a wave of new COVID-19 infections.  The government announced Monday that soldiers, police and border guards will be deployed to enforce the lockdown, which takes effect Thursday and mandates that most of its 168 million residents remain indoors, except for those who work in Bangladesh’s critical garment industry or other essential services. Tens of thousands of migrant workers are scrambling to evacuate the capital, Dhaka, before the lockdown goes into effect.   The country reported a record-high 119 coronavirus related deaths on Monday.   COVID-19 vaccine updates A handful of new studies is providing welcome news in the fight against COVID-19. A new study conducted by scientists at Oxford University suggests that mixing the Pfizer and AstraZeneca vaccines in a two-shot regimen will provide a higher level of immunity against the disease than both doses of AstraZeneca, regardless of the order they were given.   FILE – A nurse fills a syringe with the AstraZeneca COVID-19 vaccine at a health care center in Seoul, Feb. 26, 2021.A separate Oxford study shows a third dose of the AstraZeneca vaccine produced a strong immune response.  The vaccine, which was developed jointly by AstraZeneca and Oxford, is given as two doses between four and 12 weeks apart. The study involved 90 volunteers in Britain who received a third dose of AstraZeneca after participating in the initial clinical trial last year.  Meanwhile, researchers at the Washington University School of Medicine in St. Louis said Monday in a study published in the journal Nature that the COVID-19 vaccines developed by Pfizer and Moderna may protect a person against the disease for years. The study suggests that people who received either of the vaccines, which were developed through the messenger RNA technology, may not have to receive a booster shot.   Dr. Ali Ellebedy, the study’s lead researcher, said a person’s immunity is still highly active even 15 weeks after receiving the first dose of either the Pfizer or Moderna vaccine.  He said a person’s immunity typically declines after one or two weeks after vaccination.  Dr. Ellebedy said the study did not consider the one-dose Johnson & Johnson vaccine, but he said he expected the immune response from that vaccine to be less durable than those produced by the mRNA vaccines.  As of early Tuesday, there are 181.3 million confirmed COVID-19 infections around the world, including 3.9 million deaths, according to Johns Hopkins.  The United States leads both categories with 33.6 million confirmed cases and 604,114 deaths. India is second in the number of total infections with 30.3 million, followed by Brazil with 18.4 million.  The positions are reversed in the number of fatalities, with Brazil in second place with 514,092 and India in third with 397,637.  
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