Covid vaccines – Why we need more than one iron in the fire
by Guest Author on 18 Nov 2020
As reports of new COVID-19 vaccines offer us “hope in a vial”, MRC Executive Chair Fiona Watt explains why it’s so important to have multiple vaccines in the pipeline.
Many of us have breathed a huge sigh of relief following the recent, long-awaited news of two vaccines for COVID-19. Although the results are still preliminary, both the Pfizer and BioNtTech vaccine and the US company Moderna’s vaccine announced earlier this week look to be really effective – 90% and 95% respectively – in protecting people from the virus.
Although these vaccines are first past the post, many academic groups and pharmaceutical companies are still sprinting to the finish line, building on existing research involving other coronaviruses such as MERS. Currently there are 52 vaccines in clinical trials on humans, and at least 87 preclinical vaccines are under active investigation in animals.
One very exciting aspect of this news though, is that both of the vaccines are messenger RNA (mRNA) vaccines. If approved, they will be the first ever vaccines of their kind.
Vaccines work by stimulating the immune system to react to harmless proteins or killed viruses: when these enter the body, they provoke a specific adaptive immune response, with the stimulation of T-cells and the release of antibodies that can grant long-lasting immunity. An mRNA vaccine works by introducing viral messenger RNA into your cells, where it is used to make harmless copies of viral proteins, which then trigger the immune system to react and remember that particular virus for next time.
If the mRNA vaccines are approved, they may usher in a new era of vaccine production that could have immense benefit far beyond the current pandemic. This is because mRNA vaccines can be mass-produced more quickly, with production costs that are much lower than traditional vaccines. Although these mRNA vaccines are the first of their kind, scientists have been working on this approach for a long time and they will be subjected to the same rigorous safety tests as traditional vaccines.
But the Pfizer/BioNTech and Moderna vaccines come with their own issues. The Pfizer/BioNTeck vaccine must be stored at -70oC and transported in dry ice (although it can be kept in a standard fridge for five days), which will pose tricky logistical challenges not only in the UK but also in hotter climates. Moderna’s vaccine is easier to store – it can be kept at minus 20C for up to six months and kept in a standard fridge for up to a month. The vaccines must be administered in multiple doses, three or four weeks apart – this might pose a problem if people do not show up for a second dose. These challenges, of course, are not impossible to overcome.
The Oxford vaccine candidate currently in the pipeline, part-funded by UKRI and manufactured by AstraZeneca, is built on an existing platform known as ChAdOx1 that has already been assessed for safety. The Oxford team, led by Professor Sarah Gilbert, have engineered ChAdOx1 to make a specific coronavirus protein, known as the Spike protein, from the SARS-CoV-2 virus. This is the same protein as made by the mRNA vaccines. As a result, after vaccination our immune system should recognise the Spike protein as ‘foreign’ and form antibodies against it, and then attack the SARS-CoV-2 virus and stop it from causing an infection.
Professor Gilbert was previously funded by the research councils (MRC and BBSRC) and government (DHSC) through the UK Vaccine Network, and used the ChAdOx1 vector in a Phase 1 trial against the Middle East Respiratory Syndrome (MERS) coronavirus. This work was vitally important in showing the safety and effectiveness of the ChAdOx1 platform and is why her team was able to develop a COVID-19 vaccine candidate so quickly. Pre-clinical tests on animals were supported by BBSRC-funded scientists at the Pirbright Institute, while the UKRI/NIHR Rapid Response Call investment, with MRC providing the secretariat, provided the momentum to accelerate the project. This was followed by further investment from government and pharmaceuticals.
The UK government has ordered nearly 340 million doses of COVID-19 vaccines from six different manufacturers, with the hope that at least one will prove successful in large clinical trials over the next few months. 40 million of these orders are for the Pfizer/BioNTech vaccine, while 100 million are for the Oxford/AstraZeneca vaccine. The government also announced this week that from Spring it will have five million doses of the Moderna vaccine, enough to vaccinate 2.5 million people. The UK is poised to begin a large-scale vaccination programme as soon as any vaccine is approved by the relevant regulatory authorities.
The success or failure of any public vaccination programme will rely on public willingness to be vaccinated. This is why information on how COVID-19 vaccines are developed and tested, including their safety and efficacy, must be communicated clearly to the public. We must also remember that a vaccine may only work to reduce the incidence of severe disease, which may mean people can still have mild disease and transmit it to others when vaccinated.
It’s a good idea to hedge our bets when it comes to vaccine development – the more vaccines we have available, the more options we’ll have to protect as many people as we can.
Find out more about the work we have funded into developing safe vaccines for COVID-19 and identifying treatments for patients.