Can you take different COVID-19 vaccine doses?
Vaccination drives have been brought to a halt in many Indian states owing to a vaccine supply shortage, leaving many possibly without getting their scheduled doses or vaccines of their choice.
While there's no harm in delaying vaccination appointments for a given while and the recent tweak in guidelines will allow more people to get partially inoculated against coronavirus, a frequent question which pops in a lot of people's mind is, could they mix and match coronavirus vaccines?
Given the problem of acute shortage we are facing, would it be alright to take one dose of Covaxin and one dose of Covishield? Would vaccination still be effective?
What happens if you miss your second vaccine dose?
A person needs two full doses of any COVID-19 vaccine to secure full protection, so, skipping the second dose is not an advisable option.
It's also important that a person gets their second COVID-19 dose as per recommended dosing gaps, and try, and avoid delaying the appointment too much.
However, if due to unforeseeable circumstances, such as shortage, a person is unable to get the second vaccine dose on time, one should not worry too much. Not getting the second dose will not render the first dose useless. While it is critically important to get the second jab as per recommended timelines, try and schedule the dose as and when you can, but do not cancel it. Even if you do get late, do get the second dose and continue to practice mask hygiene and COVID appropriate behaviour.
Should you mix two vaccines together? What do experts say?
As crucial as vaccinating the masses is, the skewed availability of vaccine doses will corner people into deferring vaccination. Still, some experts opine that vaccination doses should not be mixed, no matter what.
A prime reason behind saying so is that all vaccines are made differently, and work in a different way. For example, mRNA vaccines (messenger RNA) deliver an immune response in a different manner than traditionally modelled vaccines, such as Oxford-Astrazeneca, or our homegrown Covaxin. Therefore, at a time like this, mixing and matching doses may not prove suitable outcomes.
Different vaccines may provide different responses
Even with combining two vaccines of the same nature, such as traditional makes like Covishield and Covaxin, there may be a possibility that the results won't be favourable.
Secondly, beneficiaries should also keep in mind that some vaccines may be less 'safer' or less suited to them. For example, somebody with a pre-existing risk of blood clotting disorders, allergy risk or using any blood-thinning medications may want to avoid taking the risk. Side-effects, suitability, antibody response are all factors to be taken care of.
Therefore, ideally, mixing or matching doses, or getting a different second dose than the first one is not recommended.
Have vaccines been combined for use before?
While the vaccines against coronavirus have been rolled out experimentally in a race against time, this is not the first time the idea of mix and matching vaccines have been toyed with. Scientifically speaking, the mix-and-match strategy is known as a 'booster' of sorts or heterologous prime and in the past, has been deployed for use in infectious outbreaks like that of Ebola.
Trials are underway to determine the effectiveness
While expert opinions remain divided, there are some current trials going on which are working to test if using doses of two different vaccines would provide stronger prevention and immunity against the infection.
For example, a recent clinical study done on 600+ participants evaluated the effect of combining doses of the Oxford-Astrazeneca (Covishield) and the Pfizer mRNA vaccine. Early observations found that not only was the combination tolerable, and provided a sufficient potent immune response against the infection.
A similar study has been planned to study the effectiveness of combining Moderna and Novavax COVID-19 vaccine jabs.
Research, conducted out of Spain also observed that the combination trial did not really defer, or change antibody response fueled by vaccination.
What people need to remember
Our country is facing critical vaccine shortages. However, the bottom line remains that the idea which looks good on paper, may not be that well-suited in real life.
At a time like this, while the focus remains to fix the gap and further prioritize those getting the second jab, mixing vaccine doses may not be actually better than not getting a second dose. Most of all a decision best left to medical experts.
Even though current government experts have attested that mixing vaccines is 'theoretically' possible, do remember that there's not much that we know about the same. Hence, decisions should not be taken in haste by beneficiaries.
Instead, the priority should be done so that all eligible people secure at least one dose of the vaccine, which will offer some level of protection. Therefore, precaution is advised at all steps.