T-cells provides the response to the infection.
Antibodies provides the immunity to the infection.
Usually when someone talks about
T-Cell Immunity (cross reactive memory)...its a conversation about
"reactivation of the T-cells" in people that had no known prior exposure to Covid-19.
- It impacts the severity of the disease and can be used to determine the viral spread in the population.
The above is only part of the immunity equation.
There's also
Antibody Immunity (sometimes refer to as seasonal immunity). This can be tested via a lockdown of the population and then the re-opening (removing the lockdown).
If infections begin to rise after removing the lockdown...one can assume there's no antibody immunity. In contrast, if infections began to decline after removing the lockdown...one can assume there's antibody immunity.
I think people get T-cell Immunity and Antibody Immunity mixed up.
With that said, this is about Sweden.
- Has Sweden achieved Herd Immunity ?
There's many articles / studies that say Sweden has
not achieved herd immunity...they have not and one of those articles is posted below.
https://www.webmd.com/lung/news/20200813/swedens-no-lockdown-policy-didnt-achieve-herd-immunity
Some studies say up to one year of immunity, others say about 6 months of immunity. The key to remember, Covid-19 is a new type of Coronavirus although Coronavirus is not new. Simply, what they tell you today, it'll most likely change next week including research results.
I predict, Covid-19 vaccinations will be given every few years to control its spread just like the FLU.
Sweden's deaths and ICU admissions have declined considerably since June, likely due to protections for nursing-home residents and more social distancing over the summer months. But cases could still climb again as schools reopen, nursing homes allow visitors, and people return home to cities after summer vacation.
Obviously, Sweden does not have Herd Immunity while its Scandinavian neighbours still do not have death counts near that of Sweden. Therefore, when a vaccination is develop for the world...Sweden will obviously look back to see if their high death count and targeted restrictions (tighter measures) was worth it.
wrbtrader