Which vaccines are winning the race to tame the COVID-19 pandemic?

By Mark Lynas

December 1, 2020

Two – possibly three – vaccine candidates have now almost made it through trials and regulatory approval, with the first vaccinations due to start within days. It is too early to say the COVID pandemic is almost over, but there is certainly light at the end of the tunnel.

(This post updates our earlier archived post about the most promising candidate vaccines and the platforms — from RNA to inactivated COVID viruses — that they use.)

Oh, and no you shouldn’t be worried that it’s all happened too quickly.

Here’s the profiles, and the latest:


As our colleague Justin Cremer reported, BioNTech/Pfizer scored a big win in the initial results of their Phase III trials. According to data released on 18 November, their mRNA-based vaccine is at least 95% effective in preventing infection with COVID-19 after tests in more than 43,000 people. The testing regime involved an initial shot followed by a booster. Importantly, the study monitors have not reported any serious safety concerns.

BioNTech has already applied for approval in the UK, which could see the first vaccinations taking place from 7 December. Emergency US approval could come by 8-10 December, with shipments of the vaccine starting within 24 hours of any announcement.

mRNA vaccines are an entirely new technology, which use messenger RNA to get human cells to produce COVID viral proteins in the body to trigger an immune response rather than injecting them from outside. Phase 1 and 2 trials produced promising data, with the subsequent results reported in Nature in August. mRNA vaccines have the advantage that they should be easy and quick to tweak should the virus mutate significantly.

With the US and many countries inEurope in the midst of a devastating coronavirus second wave, the timing of a vaccine release is of intense interest. The companies say they “expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021”. Many countries, like the UK, which have already ordered millions of doses of the vaccine in advance, are already planning who will be the first to receive it – the elderly and those working in the health care sector.


On 16 November Moderna also reported preliminary Phase III data – and the news was just as good as for the Pfizer vaccine, with an efficacy rate of around 95% in preventing COVID-19. Both vaccines use similar mRNA technology. Final results, released at the end of November, confirmed a 94% efficacy rate and 100% success in preventing severe COVID.

Moderna requested ’emergency use authorization’ from the US FDA on 30 November, and is also applying for marketing authorization in Europe.  The company says it will have 20 million doses of mRNA-1273 ready to ship by the end of 2020, and that it remains on track to manufacture 500 million to 1 billion doses globally in 2021.

Another mRNA player is CureVac, which posted promising Phase I results in early November. Although it is some way behind both Moderna and Pfizer, it claims to have produced a better immune response and will be well-positioned to deliver large numbers of lower-dose vaccines in the second quarter of 2021.

Oxford/AstraZeneca’s AZD122

AstraZeneca’s prospective COVID-19 vaccine uses a weakened form of a common cold virus (called an adenovirus) that usually infects chimpanzees. It is genetically altered to carry some of the code for key proteins in the SARS-CoV-2 virus, thereby eliciting a protective immune response in humans.

This vaccine is now in Phase 3 trials in the United Kingdom, Brazil, South Africa and the United States. Preliminary data released on 23 November suggested that – for one dose regime at least – 90% efficacy could be found, while averaged over two dose regimes the efficacy rate was 70%.

Earlier, on 16 November the Oxford team announced results of a Phase 2 trial which showed that the ChAdOx1 nCoV-19 vaccine performed well in stimulating an immune response in older adults. The results, published in The Lancet, showed both T-cell and antibody responses.

AstraZeneca says it is ramping up towards a global production capacity of 3 billion doses in 2021 on a rolling basis, assuming regulatory approval is achieved – it will start by seeking an Emergency Use Listing from the World Health Organization for an accelerated pathway to vaccine availability for developing countries. Unlike the mRNA vaccines produced by Moderna and Pfizer, which require extreme deep freeze, the Oxford vaccine can be stored, transported and handled at normal refrigerated conditions (2-8 degrees Celsius/ 36-46 degrees Fahrenheit) for at least six months and administered within existing healthcare settings.

Sinovac and Sinopharm

These Chinese COVID vaccine candidates use the tried-and-tested method of inactivated viruses as a vaccine. Sinopharm is currently running a Phase 3 trial among 15,000 people in Abu Dhabi, while Sinovac is running a trial in 9,000 health care professionals in Brazil. This trial was halted on 10 November due to the death of a participant; however when this was found to have been a suicide the trial was restarted the following day. Phase 1/2 trial results were published in The Lancet Infectious Diseases in mid-November – the study authors reported that the vaccine was safe and “generated robust antibody responses” in patients.

In November the state-owned company Sinopharm said that out of 56,000 people who had received its vaccination and travelled abroad, none had been infected with coronavirus – anecdotal evidence to complement formal Phase III trials currently ongoing in UAE, Egypt, Bahrain, Peru and Morocco. Hundreds of thousands of Chinese have already received the vaccine, according to reports.

Johnson & Johnson

Like the Oxford vaccine, J&J’s vaccine also uses genetically-engineered adenovirus as a vector, a technology it has already successfully deployed in its fully approved Ebola vaccine. In September the company launched Phase III trials with 60,000 volunteers across three continents to study the efficacy of its COVID vaccine versus a placebo. The company is scaling up manufacturing and plans to have a billion doses available next year, which could be rolled out after ’emergency use authorization’ is achieved in early 2021. The vaccine, which is catchily titled JNJ-78436735, is the first single-dose COVID-19 candidate to enter Phase III trials. All the other candidates are likely to require an initial shot followed by a booster.

Russia’s ‘Sputnik V’

Russia, of course, already claims to have won the vaccine race. Launched as always with an eye to Soviet-style propaganda, the so-called Sputnik V vaccine hadn’t yet completed standard Phase 1 and 2 testing and Russia’s regulator later walked back on the announcement. The test results have since been published in the Lancet and look reassuring — the safety profile was good and a strong immune response was seen. However, some researchers have since raised questions about apparent duplications in the data and other concerns.

The vaccine is another adenovirus vector approach and is being developed by the Gamaleya Research Institute, part of Russia’s ministry of health. A 40,000-person formal Phase 3 trial is now underway in Russia.