Covid-19 vaccines: Questions about the unknown

There are many unknowns when it comes to Covid-19 vaccines, especially on timing , dosage and long-term protection.

Tit-for-tat squabbles over who has the best regulatory and approval system are an unhelpful distraction that risk undermining trust in what are a series of rapidly emerging vaccines approved in record time.

In contrast to lingering doubts, it should be underlined that the three lead candidates – from Pfizer/BioNTech, Moderna, and Oxford University/AstraZeneca – are so far indicating striking efficacy in the level of protection they provide.

So will the Covid-19 vaccines that we know work stop contagion?

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Unfortunately, we don't know yet. Theoretically, they might not. What we can say at this point, according to UCC-based vaccine specialist Dr Anne Moore, is they will stop infection – that is ensure people don't get the disease. "We cannot say they will stop transmission."

The key priority is protecting the individual, most notably those at greatest risk. That said, if up to 70 per cent of the population gets vaccinated, herd immunity is realisable, she notes, driving down transmission.

How long will protection last?

It’s too early to know. Additional research is needed; the answer is likely to emerge with scaled-up vaccination and follow-up monitoring.

However, it is encouraging that available data suggests most people who recover from Covid-19 develop an immune response that provides at least some protection against reinfection – though we’re still learning how strong this protection is and how long it lasts.

The uncertainty is because the world is wrestling with a novel coronavirus. Research from the 1990s with a mild coronavirus found reinfection occurred after a year but too much cannot be read into this, Dr Moore adds. So an annual booster dose is a possibility.

Is it likely we will have to get multiple doses with the initial vaccine?

The initial range of vaccines being tested are using a two-dose regimen, some weeks apart. Johnson & Johnson is testing a single-dose vaccine.

A two-dose regimen comes with supply-chain challenges and the possibility that not everyone will return for a second jab. So a robust system of administration is required.

Will some be easier to administer than others?

It is clear that the much-vaunted Pfizer-BioNTech mRNA vaccine, already cleared for use in the UK, will probably have to be administered in specialised settings as it must be stored at up to minus 80 degrees and needs to be reconstituted before being administered.

That said, mRNA vaccines, which have never been used in humans before, are surprisingly straightforward: they’re just a smart way of getting a viral protein to generate an immune response, and after a few days the mRNA is degraded by the body, leaving behind only immunity to Covid.

To generate a good immune response, two doses will be given 21 days apart, with recipients protected from about a week after their second dose.

The Oxford University/AstraZenaca vaccine does not require low temperature storage, so will be much easier to administer.

When will we see Covid-19 vaccines?

Vaccine rollout in the State depends on EU regulatory approval. The first tranche is likely to get the green light in late December/early January.

The vaccine taskforce, led by Prof Brian MacCraith, is due to deliver a plan shortly on how vaccines will be rolled out and who will be prioritised .

GPs and pharmacists are likely to join the ranks of immunisers but mass vaccination clinics are likely to be set up. Nine ultra-low freezer lorries have arrived in the country to assist in rollout .

Ideally, Moore says, vaccines should be self-administered by using an arm patch or taking a tablet but these are next-generation versions, so vaccination by injection will be the standard approach with Covid-19.

When will a sense of some normality emerge for the average person?

The impact of Covid-19 vaccines on the pandemic will depend on their effectiveness; how quickly they are approved, manufactured and delivered – and how many people get vaccinated. Most scientists anticipate that, like most other vaccines, they will not be 100 per cent effective.

The first priority has to be healthcare/frontline workers, older people and the medically vulnerable – and securing vaccines for that cohort in the first half of 2021.

Unfortunately, however, until herd immunity is achieved “there is no going back to normal” Dr Moore stresses; so social distancing, facemasks and washing hands will still be the non-pharmaceutical way of keeping Covid-19 at bay. All going well, those at least risk are likely to be vaccinated from the third quarter of 2021 on.

The one certainty is Ireland will have enough Covid-19 vaccines; some 15 million doses from six manufacturers who have reached a supply agreement with the EU, subject to regulatory approval.