Normal life in the spring? What to expect from the first COVID-19 vaccines
All we can really hope for is that these vaccines will provide temporary protection for some people.
After news that Pfizer's COVID-19 vaccine was showing signs of 95% effectiveness, many were excited about the end of the pandemic. Sir John Bell, a professor of medicine at the University of Oxford, even suggested that life could be back to normal by spring.
The news from Pfizer is absolutely fantastic. The vaccine against COVID-19 may well be approved and ready for use in the next few months. But it's less likely that we can all return to normal in early 2021.
If we have a highly effective vaccine that stops the transmission of the virus from person to person, and it can be spread around the world, it will have a huge impact on the fight against COVID-19. But, probably, this is still far away.
Given that we do not know exactly what the effect of these early vaccines is, and the logistical challenges of vaccinating billions of people around the world, it is more likely that the first vaccines will be just one of the tools we continue to develop to combat the coronavirus.
Working with unknowns
All leading vaccines are based on the fact that the human body produces an artificial form of the spiked protein of the virus, which protrudes above its surface and is easily recognized by the immune system.
These vaccines contain genetic instructions on how to create a spike protein and deliver it to cells in the body using either a molecule called mRNA or an altered version of another harmless virus. The cells then make copies of the spike protein to which the immune system must respond. Having learned and memorized what the outer parts of the virus look like, the immune system should be able to react quickly to the real virus in the future.
One of the advantages of this tactic is that it eliminates the need to expose people to the entire virus during vaccination, and therefore should be safer. It is also a potentially faster path to creating a safe and effective vaccine than traditional methods that use the entire virus.
However, the development of vaccines using mRNA or viral vectors is a new field. Viral vaccines based on these methods are not widely used yet, so we are not sure how good they are.
Interim results from the Pfizer vaccine, which uses mRNA to deliver its genetic instructions, suggest it could be very effective, but we still have a lot to find out. First, these are not definitive results, and it is important to remember that test performance and real-world performance are not necessarily the same. We also don't know yet if Pfizer's vaccine actually stops people from transmitting the virus.
If the Pfizer vaccine and other vaccines that are nearing completion pass safety and efficacy tests in the next few months, it's a good idea to try them out. But it is too early to say whether they will stop the transmission of the virus in enough people for us to achieve herd immunity.
Perhaps COVID-19 vaccines based on more proven methods, such as the Valneva vaccine, which uses an entire killed version of the virus, will eventually prove most effective. However, the Valneva vaccine is unlikely to be ready for approval until at least mid-2021.
We also don't know how long the immunity provided by these vaccines will last. We know that antibodies produced after a natural COVID-19 infection can disappear within a few months. Antibodies induced by the vaccine can also disappear quickly.
However, antibodies are probably not a complete response to the body's response to this (and even other) coronaviruses. Another type of immune response - involving T cells-is also important. Both Pfizer and AstraZeneca vaccines have been shown to induce a T cell response. But we don't know yet if these responses will last.
These first COVID-19 vaccines may be imperfect, but imagine that half of those vaccinated will have a strong enough protective response to stop transmission of the virus. This will certainly help our efforts to combat it.
But from what we know about SARS-CoV-2, it is clear that at least 70% of the population must have a strong and sustained immune response for the virus to die out completely. Aside from not knowing how long a vaccine-induced immune response can last, there are other factors that make it difficult to achieve this.
Some people do not accept vaccines, others cannot get vaccinated due to existing diseases. Some people will refuse to get vaccinated.
Achieving 70% coverage would also require the mass production of billions of doses. AstraZeneca said it has the capacity to produce 2 billion doses of its vaccine, while Moderna says it could have 1 billion doses ready by the end of 2021. By then, Pfizer may have 1.3 billion doses, although recipients will need two doses. This does not allow us to vaccinate enough people.
And it will be difficult to organize the transportation of these vaccines around the world and their delivery to all people in need. For example, the Pfizer vaccine must be stored at -80° C. Even in developed countries this can be a problem, not to mention in countries with limited resources. It will definitely take more than a few months to roll out a vaccination campaign.
All we can really expect from the first vaccines is that they will provide temporary protection for some people. This, of course, will help a little, but only within the framework of a set of measures. We will have to continue social distancing and hand hygiene for some time yet — and expect masks to be present in the fall/winter 2021 fashion collections.