Experts comment on early COVID vaccination rollout

Australia’s coronavirus vaccine rollout will be brought forward to next month, with Prime Minister Scott Morrison saying the first groups are expected to receive the jab in mid-to-late February. The PM said the first groups to receive the vaccine would be workers dealing with international arrivals and quarantine, frontline health workers, aged-care and disability workers, and those living in aged care or with a disability.

Professor Raina MacIntyre — Head of the Biosecurity Program at the Kirby Institute at the University of NSW — is an expert in influenza and emerging infectious diseases, and described the earlier rollout as excellent news.

“The international border is the greatest threat to us, because of new mutations of the virus which may be 50–80% more transmissible than the current strain. One of these strains has become the main strain in the UK, and they are finding that the standard control measures such as social distancing are not working as well. If one of these strains takes off here, it may be more difficult to contain.

“It is critical we vaccinate everyone working at the international border with the best available vaccine — not just hotel quarantine staff, but also transport staff, aircrew, airport workers. They are the most likely vectors of infection into the community — if they are well protected with the best vaccines, we can take a breath and wait for the broader community rollout.

“They need high-efficacy vaccines like Pfizer or Moderna; the Astra Zeneca vaccine will protect them against death and hospitalisation, but may not protect well against infection — so they can still get infected and set off a community epidemic.

“Protecting workers at the border is the most critical step to protect the community, and includes giving them respirators and finally accepting they are at risk of airborne infection. If the risk of community epidemics from the international border are reduced, we can wait for the population vaccination.”

Professor MacIntyre also said that the proposed earlier vaccination of health and aged-care workers was very welcome news.

For general community vaccination, Professor MacIntyre stressed the importance of using high-efficacy vaccines.

“I do not believe the Astra Zeneca vaccine, based on published phase 3 trial results, will be efficacious enough for herd immunity. We must also be mindful that the key trial endpoint to assess is the prevention of any infection (not just symptomatic infection).

“As I have explained here, I believe the elimination of COVID-19 in Australia may be feasible, if we use a high-efficacy vaccine and vaccinate enough people. We should be aiming for this — we may or may not succeed, but we should try before resigning ourselves to living with COVID long term.

“Vaccines are the best exit strategy we have for COVID-19, but the choices we make today could take us down very different pathways, depending on those choices.”

Dr Andrew S Flies — ARC Discovery Early Career Research Fellow at the University of Tasmania — agrees that a primary threat to regions that have been COVID-free for many months is the incursion of the SARS-CoV-2 virus from international travellers. “The best weapons against COVID-19 remain social distancing and masks, but vaccines offer powerful disease prevention tools, particularly for workers at international arrival and quarantine locations.

“Phase 3 clinical trial data from international studies suggest that several vaccines, including the Pfizer mRNA-based vaccine and AstraZeneca adenovirus-based vaccine, protect against severe disease. It remains unknown how effective these vaccines are at preventing transmission and reducing coronavirus in the community. However, statistical modelling efforts by Saad-Roy published in Science suggest that that vaccination may accelerate pandemic control even with imperfect vaccines and moderate vaccination rates.”

Professor Julie Leask — a social scientist whose research focuses on infectious disease and immunisation controversies and communication — from the University of Sydney Susan Wakil School of Nursing and Midwifery said that we should be cautious about welcoming the news that certain priority groups will get the vaccine early.

“This is a large complex program which requires careful planning, coordination, a well-trained workforce and an informed public. There are important logistical issues to consider. High-quality immunisation service provision is just as important as high-quality vaccines.

“The federal government should be more forthcoming about the details of how they are planning this program and coordinating with state governments, so the public can be confident in the way this program will be rolled out.

“We need to see much more proactive and frequent communication. Government may not yet have full knowledge of some aspects of the program prior to TGA approval but what is known and planned now should be communicated in more detail.”

Nikolai Petrovsky — Professor in the College of Medicine and Public Health at Flinders University and Research Director at Vaxine Pty Ltd, currently undertaking clinical trials of a COVID-19 vaccine — said, “Premature approval of COVID-19 vaccines by Australia could have major negative public health ramifications. Current approvals in other jurisdictions are Emergency Use Authorisations (EUA) and it is not clear from this announcement whether what is proposed is an EUA that restricts vaccine use to very specific populations or whether a more general approval is proposed, and if so, on what grounds?

“EUAs are typically issued on a risk–benefit basis. Australia currently has minimal domestic transmission of the virus and hence the benefits of use of novel vaccines in this context has questionable benefit versus the unquantifiable risks. The absence of any data on the long-term effectiveness and safety of mRNA and viral vector vaccines makes any general approval of use of such vaccines questionable from a community safety standpoint.

“There remain major unanswered questions regarding the effectiveness of the mRNA and adenovirus vector vaccines. Currently there is no proof that any of these vaccines prevent virus transmission as opposed to just blocking symptoms of infection. Hence the risk is that such vaccines may just be making symptomatic infections asymptomatic. This is a major concern as the use of such vaccines in workers dealing with international arrivals and quarantine could have the paradoxical effect of increasing the risk of further quarantine outbreaks into the Australian population with an infected worker thereby going undetected due to the vaccine suppressing symptoms if infected.

“Furthermore, receiving a vaccine may give such workers a false sense of security, making them more likely to engage in activities associated with higher risk of transmission to members of the community. It may also make them more likely to dismiss any mild symptoms as being non-COVID related. Similarly, disability workers and those living in aged care or with a disability are currently at low-to-no risk given the absence of community transmission. It is hard to justify immunising disability workers with vaccines that have unknown long-term efficacy or safety, given there is no evidence such vaccines are transmission blocking, which would be the only current major justification for their use in such individuals to prevent them passing on the virus to people in their care.

“While EUA of these vaccines may be perfectly justifiable in jurisdictions such as Europe and US where there is currently uncontrolled community spread of virus, with high morbidity and mortality rates, it is very hard to justify even an EUA of such vaccines in the context of the current situation in Australia, where instead it would seem to make more sense from a risk–benefit standpoint to continue to control any outbreak risks using proven quarantine, tracing and social isolation policies while awaiting stronger, longer-term efficacy and safety data to be obtained on these vaccines from their use elsewhere in the world.”

Professor Petrovsky said that Vaxine is committed to the development of its recombinant protein-based COVID-19 vaccine approach, with the aim to not only reduce COVID-19 disease but also to block virus shedding and transmission, commenting that “a safe and effective transmission-blocking vaccine remains the only viable strategy to bring this pandemic to a rapid end”.

Image credit: ©stock.adobe.com/au/Daniel CHETRONI