DOES A VACCINE AGAINST COVID-19 HERALD THE END OF THE PANDEMIC? / THE FINANCIAL TIMES OP EDITORIAL

Does a vaccine against Covid-19 herald the end of the pandemic?

More data is needed on the efficacy of treatment as the world faces challenge to vaccinate the 7.8bn global population

Azra Ghani 

     A photo from BioNTech of a Covid-19 vaccine candidate

Excitement swept the globe on Monday with the announcement of the stellar — but early — results from a vaccine candidate against Covid-19.

In its press release, the drug company Pfizer announced that its vaccine had been shown to be “more than 90 per cent effective in preventing Covid-19 in participants”. Does this mean that the end of the pandemic is in sight?

While this is undoubtedly good news, it is important to remember that this vaccine is still in the relatively early stages of testing. To understand the potential of a vaccine we need to know how efficacious the vaccine is and how long that efficacy is maintained.

The initial results tell us that the vaccine has greater than 90 per cent efficacy at seven days after the second dose is taken. Further results will follow shortly giving efficacy results at 14 days. In the coming months more data will accrue that will tell us whether this efficacy is maintained.

This will also indicate whether people will need regular yearly shots. We also have yet to learn whether the efficacy varies in different people; for example, flu vaccines are generally less effective in older people.

Coupled with data on efficacy, it is critical to know if a vaccine that will be given to otherwise healthy people is safe. Encouragingly, the Pfizer trial has not reported to date any severe “adverse events” in the 43,500 trial participants. While most vaccine-associated severe reactions occur shortly after vaccination, it will be important that trial participants — and those vaccinated following licensure — are closely followed to ensure that the benefits of receiving the vaccine outweigh any risks.

The real challenge comes next — how do we vaccinate the 7.8bn global population at risk? Under current manufacturing capability, doses of this and other vaccines under trial are likely to fall well below what is required in the near-term. 

The Covax facility — a collaboration set up by World Health Organization and partners to ensure equitable access to vaccines in low- and middle-income countries — expects to have up to 200m doses available in 2021. Several countries — including most high-income countries — have bilateral agreements in place with one or more vaccine manufacturers to supply doses in 2020 and 2021. 

But for many countries, doses are likely to be available for up to 20 per cent of the population, some way short of the 60 per cent-plus coverage that is likely required to achieve herd immunity.

Each country will therefore need to decide how to prioritise that allocation. Most countries are likely to focus on high-risk groups; those that are most vulnerable to severe outcomes such as the elderly, and those that are highly exposed such as healthcare workers. 

In the interim, it is likely that the rest of us will need to maintain social distancing, handwashing and mask-wearing to keep transmission in the community low.

There are also considerable logistical obstacles to achieving mass vaccination — something that has previously never been undertaken at this scale. The equipment for vaccination needs to be manufactured, transported from factories and delivered to local health centres; cold storage may be required along the way — the Pfizer vaccine poses particular challenges here as it requires minus 80 degree freezer storage. An army of healthcare workers will be needed to deliver the vaccine in every country.

So don’t forget that the virus is still with us and this is just the start of a long road ahead. It might just be worth putting that champagne on hold.

The writer is professor of infectious disease epidemiology at Imperial College London