AstraZeneca vaccine arrives in Aus, Pfizer prevents infection

The first 300,000 doses of the University of Oxford and AstraZeneca’s COVID-19 vaccine arrived in Sydney yesterday, ready for batch testing by the Therapeutic Goods Administration (TGA) to ensure they meet Australia’s strict quality standards.

Australia has secured 53.8 million doses of the Oxford–AstraZeneca vaccine, 50 million of which will be manufactured onshore by CSL on behalf of AstraZeneca. The vaccine has been described by the World Health Organization (WHO) as “safe and effective in preventing symptomatic COVID-19 [in clinical trials], with no severe cases and no hospitalisations more than 14 days after the second dose”.

According to Prime Minister Scott Morrison, the arrival of the first doses marks “the next step as we ramp up the vaccine rollout”.

“We will now be able to scale up the vaccination rollout to our priority groups, including our most vulnerable Australians and to our frontline border and health workers,” the Prime Minister said.

“Most Australians will receive the University of Oxford–AstraZeneca vaccine, with the rollout of these due to commence from 8 March 2021 — provided they clear the TGA’s rigorous batch testing process.”

The first 300,000 doses will be distributed via logistics partners DHL and Linfox, and made available to priority groups in Phase 1a. From late March, 1 million of CSL’s will be delivered each week, with second doses to be administered 12 weeks after the first dose.

Minister for Health and Aged Care Greg Hunt said the Oxford–AstraZeneca vaccine provides the option for the majority of Australians to get their vaccination through their usual GP, at local respiratory centres and eventually at community pharmacies.

“As the rollout begins, the people in priority groups who need the most protection will receive a vaccine first,” he said. “This includes aged-care and disability-care residents and workers, frontline healthcare workers, and quarantine and border workers.

“Having AstraZeneca available in Australia provides an easier avenue for distribution across the nation, meaning people in rural, regional and remote areas will not have to travel as far to receive their vaccine.

“The cold chain requirements of this vaccine — it can be stored and handled in the same way as any other vaccine — make it a very good candidate for a country like Australia.

“As well, vaccine providers can use some of the vaccine vial, put the rest back in the fridge for 48 hours and use the rest the next day.”

Meanwhile, new data from Addenbrooke’s Hospital in Cambridge suggests that a single dose of the Pfizer–BioNTech vaccine — which is already being rolled out to Australian priority groups — can reduce the number of asymptomatic SARS-CoV-2 infections by 75%. This implies that the vaccine could significantly reduce the risk of transmission of the virus from people who are asymptomatic, as well as protecting others from getting ill.

Researchers from the Cambridge University Hospitals NHS Foundation Trust (CUH) and the University of Cambridge analysed results from thousands of COVID-19 tests carried out each week as part its screening programs on hospital staff who showed no signs of infection. During a two-week period between 18 and 31 January 2021, the team screened similar numbers of vaccinated and unvaccinated staff using around 4400 PCR tests per week. The results were then separated out to identify unvaccinated staff and staff who had been vaccinated more than 12 days prior to testing (when protection against symptomatic infection is thought to occur).

The study, which is yet to be peer-reviewed, found that 26 out of 3252 (0.8%) tests from unvaccinated healthcare workers were positive. This compared to 13 out of 3535 (0.37%) tests from healthcare workers less than 12 days post-vaccination and four out of 1989 (0.2%) tests from healthcare workers at 12 days or more post-vaccination.

The results suggest a four-fold decrease in the risk of asymptomatic COVID-19 infection amongst healthcare workers who have been vaccinated for more than 12 days (75% protection). The level of asymptomatic infection was also halved in those vaccinated for less than 12 days. When the team included symptomatic healthcare workers, their analyses showed similar reductions.

The study was led by Dr Mike Weekes, an infectious disease specialist at CUH and the University of Cambridge’s Department of Medicine. He said, “This is great news — the Pfizer vaccine not only provides protection against becoming ill from SARS-CoV-2 but also helps prevent infection, reducing the potential for the virus to be passed on to others.

“This will be welcome news as we begin to plot a roadmap out of the lockdown, but we have to remember that the vaccine doesn’t give complete protection for everyone. We still need social distancing, masks, hand hygiene and regular testing until the pandemic is under much better control.”

Dr Nick Jones, first author on the study and an infectious diseases/microbiology registrar at CUH, added, “Our findings show a dramatic reduction in the rate of positive screening tests among asymptomatic healthcare workers after a single dose of the Pfizer–BioNTech vaccine. This is fantastic news for both hospital staff and patients, who can be reassured that the current mass vaccination strategy is protecting against asymptomatic carriage of the virus in addition to symptomatic disease, thereby making hospitals even safer places to be.”

Image credit: ©ZSOLNAI GERGELY/Dollar Photo Club

Please follow us and share on Twitter and Facebook. You can also subscribe for FREE to our weekly newsletters and bimonthly magazine.

Part of this article has been sourced and modified from a news item published by the University of Cambridge under CC BY 4.0.