[ad_1]
CORK, Ireland: Preliminary data from the Pfizer / BioNTech COVID-19 vaccine trial suggests that it is 90% effective in preventing the disease.
At the very least, this news will result in a huge sigh of relief throughout the vaccine community. It is a breakthrough: it is the first announcement that a vaccine can protect against SARS-CoV-2 infection in humans.
This shows that it can be done. But how well it can be done remains a big question that no one has the answer to. These results are promising, but there is much more that we now need to confirm.
READ: Comment: Why rushing a COVID-19 vaccine could spell disaster
QUICK FOLLOW-UP OF INTERMEDIATE ANALYSIS
The 90 percent efficacy is a strong result, but we must remember that this is an interim analysis, based on 94 cases of illness that have occurred among those who received the vaccine or a placebo.
Pfizer has stated in its testing protocol that it needs at least 164 cases of illness throughout the study to reliably assess the efficacy of the vaccine.
If subsequent cases occur more frequently among those who have received the vaccine rather than the placebo, this efficacy figure will decrease. So we don’t know yet if this number actually reflects the protective ability of the vaccine, which means that crucially we need to get to the end of the trial.
But if this is the case, why announce these interim results now?
LISTEN: The COVID-19 vaccine will be the largest product launch in history. We can make it?
Interim analysis of trial data like this is not uncommon, particularly in phase 3 vaccine trials, as it is not unusual for trials to fail during testing.
Therefore, you need to determine as soon as possible, as robustly as possible, whether it is worth continuing the test. Continuing when things are useless is a waste of resources and, in some cases, unethical.
The only way to see if continuing is the right choice is for the trial’s independent data and safety monitoring board to review some or all of the results.
A nurse shows a Covid-19 vaccine produced by the Chinese company Sinovac Biotech at the Sao Lucas Hospital, in Porto Alegre, Brazil AFP / SILVIO AVILA
For COVID-19, where time is a major constraint, many efforts have been made to incorporate interim analysis into studies in a way that provides an answer, with some confidence, in the most timely manner possible.
Therefore, this mid-term review was planned at the beginning of the trial and has served its purpose. It’s a very positive sign that testing should continue, even if the actual review data leaves us with a lot of questions.
READ: Explainer: Where are we in the COVID-19 vaccine race?
READ: Comment: COVID-19 Vaccine – Why does it take so long to develop one?
REVIEW EFFECTIVENESS AND IMMUNE RESPONSE NEXT STEPS
One key thing that these interim results don’t tell us is how long the protection lasts. Participants in this phase 3 trial received two doses of the vaccine and its efficacy was measured seven days after the second dose was administered.
This is likely to occur at the peak of the initial immune response. It will be very important to understand how long this initial protection lasts after this point.
A pessimist would expect to remain effective for at least three months. An optimist would expect to maintain high levels of protection for several years.
READ: Comment: Could Indonesia be the hub of Southeast Asia for Chinese COVID-19 vaccine?
However, realistically, this mRNA-based vaccine platform is new, so we will need time to understand if and when the initial response starts to fade. We also need to understand whether this vaccine and others in development can induce good memory responses from the immune system that will provide protection for years to come.
It is also important to identify the exact immune response that mediates protection, which are called “correlates of protection.” Is it a particular type of antibody or T cell that is involved, and what is the threshold amount of these that is needed to protect an individual?
With this knowledge, future trials can focus on measuring the amount of these immune markers in individuals to better assess whether vaccines are working.
FILE PHOTO: People wear face masks amid the global outbreak of coronavirus disease (COVID-19) at the Shanghai Railway Station in Shanghai, China, on November 10, 2020. REUTERS / Aly Song / File Photo
Another important thing to know is whether the vaccine completely prevents people from becoming infected with any virus or whether it simply makes people more effective in fighting the virus if they succumb to an infection.
This will govern whether the vaccine only prevents disease or can also prevent viral transmission. All we know at the moment is that it has reduced symptomatic cases by 90 percent.
READ: Comment: Who will get the COVID-19 vaccine being developed by Chinese companies?
THE PATH TO APPROVAL AND BEYOND
Although it doesn’t have the full picture, the US FDA has said it will consider licensing the vaccine for emergency use, prior to full approval, once the trial has collected two-month safety data on half of the participants. Pfizer expects to have it available by the third week of November.
The trial will also continue for many months, in order to reach that reliability threshold of 164 disease cases, and there will be more follow-ups to assess the safety of the vaccine and the immune responses and protection it elicits in different groups of participants. .
This should provide more transparent information and confidence about how well this vaccine works and in which populations.
READ: Comment: The challenge of keeping COVID-19 vaccines in freezing temperatures during distribution
If the safety and efficacy of the vaccine appear good, it will be submitted to regulatory agencies for full approval. The highest risk groups will be first in line for immunization.
In the UK, this will likely include nursing home residents and workers, health and social care workers and people over the age of 80, assuming the vaccine is safe and effective in these groups.
In Europe, priority groups include health and essential workers, those vulnerable to disease and the socio-economically disadvantaged.
A nurse leans from a balcony, as the spread of coronavirus disease (COVID-19) continues, in Rome, Italy, on May 2, 2020. REUTERS / Remo Casilli
But even if it passes, big challenges remain. Pfizer expects to have 50 million doses ready this year, enough to immunize 25 million people and 1.3 billion by the end of 2021.
Given the size of the world’s population, and the fact that the vaccine requires two doses, universal coverage is a long way off.
Therefore, the other vaccines in development are still equally important. We will need more than one vaccine for global coverage and to make sure we have the correct one for each age and health group.
Overall, these results are to be celebrated, but with the recognition that this is only one step along the way. We still have a long way to go before the world returns to normal, but the compass is pointing in the right direction.
CHECK THIS: Our comprehensive coverage of the coronavirus outbreak and its developments
Download our app or subscribe to our Telegram channel for the latest updates on the coronavirus outbreak: https://cna.asia/telegram
Anne Moore is Senior Lecturer in Biochemistry and Cell Biology at University College Cork. This comment first appeared on The Conversation.
