New considerations for GPs ahead of vaccine rollout

Phase 1a of the COVID-19 vaccine rollout is due to begin next week, with at-risk frontline healthcare workers and vulnerable groups set to begin receiving the Pfizer/BioNTech vaccine from Monday.
 
News of the Therapeutic Goods Administration (TGA) approving the Oxford University/AstraZeneca candidate means phase 1b – which GPs will be heavily involved in – will now also likely start as planned next month.
 
More than 5000 general practices have already expressed interest in taking part from phase 1b onwards, despite ongoing questions around logistics and vaccine efficacy.
 
Both the TGA and the World Health Organization (WHO) have recommended use of the Oxford University/AstraZeneca vaccine for all adults, although a lack of data means GPs have been advised to consider immunisation for people aged over 65 ‘on a case-by-case basis’.
 
That is because the Oxford University/AstraZeneca trial concentrated initially on effectiveness for frontline healthcare workers, many of whom were assumed to be healthy and aged 65 years or under. There is also uncertainty over its efficacy rate, which varies from 62–90% depending on the dosage used, but even this is open for debate given these rates were discovered as a result of a manufacturing error, rather than trial design.
 
Developers have begun a new wide-scale international trial and the UK rollout should also provide important real-life data soon, but there are no such concerns around the Pfizer/BioNTech vaccine, which has an efficacy of more than 95%.
 
More recently, there have been warnings about the Oxford University/AstraZeneca candidate’s efficacy against the emerging 501.V2 or B.1.351 SARS-CoV-2 variant, which is now dominant in large parts of South Africa.
 
In a 7 February release of a UK and South African study (yet to be peer-reviewed), small trial results show the Oxford University/AstraZeneca vaccine offers only 10% protection against mild-to-moderate disease for the South African variant, but gave no indication as to its efficacy against severe COVID.
 
From 2000 participants, viral neutralisation by blood serum induced by the vaccine against the B.1.351 variant were found to be ‘substantially reduced’ when compared with the original strain of the virus, leading the South African Government to suspend its rollout.
 
In Australia, it is likely that most GPs working in general practices will receive the Oxford University/AstraZeneca vaccine, with those working in respiratory clinics, hospitals and aged care likely eligible to receive the Pfizer/BioNTech vaccine as part of phase 1a.
 
While the South African variant has so far been contained to hotel quarantine in Australia, a potential 10% efficacy rate does raise some questions, in particular; what are the risks for GPs involved in the rollout who receive it, and is there a chance they could unwittingly transmit the disease to patients and other staff?
 
According to Melbourne GP Dr Andrew Baird, the risks are two way, with the potential for transmission either to GPs and staff from patients, or to patients from GPs and staff.
 
‘Many of the patients who attend general practice have conditions that increase their risk of complications, should they get COVID-19. GPs, their staff, and patients do not want to engage in transmitting [the virus] between one another,’ he told newsGP.
 
‘Therefore, GPs and their staff should be vaccinated with the best available vaccine in terms of effectiveness in preventing COVID-19, and ideally in preventing transmission.’
 
One issue, however, is that while Pfizer/BioNTech’s vaccine is superior in terms of protecting against mild-to-moderate disease, there is no evidence that either candidate approved for use in Australia is capable of stopping transmission.
 
‘The AstraZeneca vaccine is satisfactory based on current evidence, and unless there is confirmation that it is not effective against the South African strain, I think we should go ahead with the AstraZeneca vaccine for GPs and staff,’ Dr Baird said.
 
‘Data [related to effectiveness against the South African strain] have not yet been peer-reviewed and published. We need to see clinical data, not just serological data.
 
‘What are the effects on the incidence of COVID-19-related moderate-to-severe disease, and death? We don’t know, yet.
 
‘For the time being, I will pay attention to the WHO recommendation.’
 
Acknowledging the risk of aerosol transmission in an indoor setting, Dr Baird said receptionists and practice nurses in general practices are also at high risk and should be included in the same vaccine rollout as GPs.
 
‘I support the argument that [both] GPs and their staff are frontline workers,’ he said.
 
‘They see large numbers of patients every day, and these numbers will increase with GPs’ involvement in phase 1b and subsequent phases of the COVID-19 vaccination program.
 
‘The prevalence of COVID-19 and asymptomatic SARS-CoV-2 infection will be higher in the population attending general practice than in the general population, and transmission in general practice must be regarded as a risk.’
 
As for the efficacy of the Pfizer/BioNTech vaccine against the emerging variants, early studies indicate they could be more protective than the Oxford University/AstraZeneca candidate.
 
Results from a study of blood serum from 20 vaccine recipients published on 8 February, showed it is able to neutralise the South African and UK (N501Y) SARS-CoV-2 variants, including those with the rapid-spreading E484K mutation.


Associate Professor Paul Griffin believes it is too early to say whether new SARS-CoV-2 strains will impact vaccine efficacy to such an extent that Australia needs to reconsider its strategy. 
 
The study authors used three SARS-CoV-2 viruses containing the spike mutations from the UK and South African variants, and concluded that the ongoing evolution of coronavirus calls for ‘continuous monitoring’ of vaccine efficacy against emerging strains, as well as an understanding of whether the current vaccine candidates can provide protection against the mutations.
 
Associate Professor of Medicine at the University of Queensland and Director of Infectious Diseases at Mater Health Services, Paul Griffin, said although the study results are ‘certainly promising’ he agrees that ongoing monitoring is needed.
 
‘It is too early to change position with respect to any of the vaccine candidates likely to be administered in Australia,’ he said. ‘But we do need to carefully monitor the situation and all available evidence moving forward.’
 
Associate Professor Griffin said that when new strains emerge it is important to understand the impact of these changes.
 
‘Not only the phenotype and therefore epidemiology of the virus, but also how the efficacy of vaccines – and potentially therapies – are impacted,’ he said.
 
‘We are now hearing many such reports from the leading vaccine candidates. However, thus far the majority have been relatively small studies, yet to be peer-reviewed, and not really set up in a controlled way to truly allow head-to-head comparison of efficacy rates.

‘There are also many laboratory studies that provide very useful information, but this does not always translate perfectly to tell us what is likely to happen in the real world.’
 
While these studies confirm that more work needs to be completed to understand the effect of vaccines against the new variants of the virus, the current and emerging vaccine platforms should allow for vaccine design to be quickly updated to combat new strains as they emerge.
 
Aside from uncertainty over vaccine efficacy against new strains, Dr Baird also noted there is ongoing confusion around herd immunity.
 
‘The percentage of the population that must be vaccinated to achieve herd immunity depends on the population, the disease, and the vaccine. It’s not a one-size-fits-all figure,’ he said.
 
‘At this stage, Australia will not be vaccinating 22% of its population [under 18s] so the maximum percentage of the population that will be vaccinated is only 78% – too low for herd immunity against COVID-19.
 
‘There are many known unknowns and unknown unknowns about the vaccines. It is inevitable that efficacy will decrease as new variants emerge [and] it is likely that booster doses will be required, but at this stage we do not know what boosters will be required, or how frequently they should be administered.
 
‘For the time being, I think we have to go along with the principles of safety first, and efficacy as good as possible.
 
‘Something is better than nothing, provided [it] has adequate efficacy.
 
‘We need to consider the effects that vaccination has on the whole population and on the demand on health services, not just the effect that it has on reducing an individual’s risk of getting COVID-19.’
 
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