One other day, one other announcement a couple of COVID-19 vaccine. Whether or not that’s discuss of outcomes from medical trials, emergency approval or plans for international locations to prioritise sure teams for vaccination.
However we nonetheless don’t know if present vaccines forestall illness and in addition forestall individuals transmitting the virus to others.
This not solely has implications for vaccines we’ve been listening to about not too long ago, however vaccines nonetheless in growth.
Right here’s why stopping viral transmission is so necessary. And right here’s what we nonetheless must do whereas we await a vaccine that stops viral transmission.
Stopping illness vs viral transmission
The Pfizer/BioNTech COVID-19 vaccine has been proven to be secure and efficient in late-stage medical trials at stopping COVID-19, together with extreme illness, after an infection. However we nonetheless don’t know if the vaccine prevents transmission of the virus from an contaminated particular person to a wholesome one.
In reality, in keeping with stories thus far, this was not an endpoint or consequence measure of its trial. In different phrases, the vaccine trial was not designed to search out this out.
Nevertheless, it isn’t shocking we wouldn’t have this data at this stage. It will not be possible to find out whether or not the vaccine prevents unfold in a trial involving about 43,000 contributors. This would want routine testing of trial contributors, an enormous endeavor.
So, for us to get the sort of data, drug corporations, public well being applications and researchers might want to work collectively to assemble information as soon as the vaccines are rolled out into the neighborhood.
This may be a part of illness surveillance in a inhabitants. Alternatively, we may monitor a specific group, or location, containing individuals at excessive threat of viral transmission. Both approach, this group (or cohort) would have to be monitored over time, and their an infection standing in contrast with whether or not or not that they had the vaccine.
Then there’s the Oxford/AstraZeneca vaccine trials. There may be early indication this vaccine could scale back person-to-person transmission of the virus. The investigators pointed to the noticed discount in asymptomatic infections among the many vaccine recipients.
Though, it’s nonetheless not sure to what extent asymptomatic individuals can transmit the virus and the way a lot of a discount in person-to-person transmission could possibly be attributed to the vaccine. We want additional evaluation to know for certain.
We nonetheless don’t know if herd immunity is feasible
We nonetheless have no idea whether or not the COVID-19 vaccines are appropriate for all neighborhood members together with these with sure well being circumstances or who’re pregnant. Nevertheless, the idea is that if we vaccinate a essential proportion of the inhabitants, we are able to shield the unvaccinated, by way of herd immunity.
However we can’t inform, at this level, whether or not herd immunity in a specific neighborhood is achievable by way of COVID-19 vaccination, given we have now not seen strong proof present vaccine candidates are halting transmission of the virus.
It’s also too early to understand how properly the COVID-19 vaccines work in several populations — such because the aged, kids, pregnant ladies, and in some racially and ethnically various populations — as these teams weren’t a serious a part of and even concerned within the medical trials we’re now getting outcomes from.
Lastly, we nonetheless have no idea how lengthy the immunity developed from the COVID-19 vaccines will final.
What are the implications?
The excellence between vaccines that forestall the event of the illness and those who additionally forestall viral transmission has many implications.
As an example, as a result of we have now but to see strong proof present vaccine candidates scale back viral transmission, there’s a threat vaccinated individuals might imagine a vaccine presents extra safety than it does, and will unfold the virus to unvaccinated individuals, maybe by not sustaining correct hygiene, socially distancing or sporting masks the place wanted.
There’s additionally a threat people who find themselves unvaccinated could develop a false sense of safety. They might assume vaccinated individuals round them have developed immunity by way of vaccination to forestall transmission, or assume they’re protected by way of herd immunity.
So future COVID-19 vaccines ought to focus extra on the prevention of the transmission of the virus plus stopping growth of the illness.
In preclinical, and early-stage medical trials, the vaccine has proven a excessive degree of immune response, offering safety from an infection and illness. Nevertheless, additional evaluation is required to know the small print.
Our lives received’t ‘return to regular’ simply but
With all this uncertainty, it can be crucial we’re sensible when fascinated about what 2021 will appear to be.
Even with the discharge of the vaccine, we’re solely half-way again to regular. Hygiene, bodily distancing, the necessity for COVID-19 testing and different public well being measures will proceed to be essential.