03/05/2021 10:17
Clarín.com
Good Life
Updated 03/05/2021 12:19 PM
Does vaccination completely prevent infections?
The short answer is no.
You
can
still get
infected after getting the vaccine
.
But your chances of becoming seriously ill are slim to none.
Many people think that vaccines work as a shield, preventing a virus from infecting cells completely.
But in most cases, a person who gets vaccinated is protected against disease, but
not necessarily against infection
.
Each person's immune system is a little different, so when we say that a vaccine is 95% effective that only means that 95% of the people who got vaccinated will not get sick.
These people could be completely protected from infection, or they could be infected
but remain asymptomatic
because their system clears the virus very quickly.
The remaining 5% can become infected and sick, but such people are unlikely to be hospitalized.
Vaccination does not prevent infections 100%, but in all cases it gives the immune system a
great advantage
against the coronavirus.
Whether it is complete protection against infection or, if you develop any level of illness, you will always be better after receiving your dose of vaccine than if you had not received it.
Does infection always mean transmission?
Transmission occurs when enough virus particles from an infected person enter the body of another uninfected person.
In theory,
anyone infected could transmit the virus
.
But vaccination will reduce the chance of this happening.
In general, even if vaccination does not completely prevent infection, it
will significantly reduce the amount of virus
that comes out of the nose and mouth and shorten the time the virus is shed.
This appears to be the case for coronavirus vaccines.
In a previous recent study that was not yet peer-reviewed, Israeli researchers screened 2,897 vaccinated people for signs of infection.
Most had no detectable virus, but people who were infected had a quarter as much virus in their bodies as unvaccinated people who were tested at similar times after infection.
Fewer coronavirus viruses means
less chance of spreading it
, and if the amount of virus in your body is low enough, the chance of transmitting it can reach almost zero.
However, researchers don't yet know where that cutoff is for the coronavirus, and since vaccines don't provide 100% protection against infection, experts recommend that people continue to wear face masks and maintain social distancing measures even afterward. to be vaccinated.
Vaccines prevent disease, not necessarily infection.
Photo NIAID / NIH via AP
What about the new variants of the coronavirus?
New variants of coronavirus have emerged in recent months, and recent studies show that vaccines are less effective against some, such as the B1351 variant first identified in South Africa.
Every time SARS-CoV-2 replicates it gets new mutations.
In recent months, researchers have found
new variants that are more infective
, which means that a person needs to inhale less virus to become infected, and other variants that are more transmissible, which means that they increase the amount of virus a person gives off.
And the researchers have also found at least one new variant that appears to have an easier time evading the immune system, according to early data.
So how is this related to vaccines and transmission?
For the South African variant, the vaccines still provide
more than 85% protection against a severe disease of COVID-19
.
But when mild and moderate cases are counted, vaccines provide, at best, only about 50% -60% protection.
That means that at least 40% of vaccinated people will still have a strong enough infection and enough virus in their body to suffer from at least moderate illness.
If vaccinated people have more viruses in their bodies and it takes less virus to infect another person, there will be a
greater chance that a vaccinated person can transmit these new strains
of the coronavirus.
If all goes well, vaccines
will very soon reduce the rate of serious illness and death
around the world.
Undoubtedly, a vaccine that reduces the severity of the disease also, at the population level, will reduce the amount of virus that is transmitted.
But due to the emergence of new variants, vaccinated people still have the potential to
spread and transmit the coronavirus
to other people, whether they are vaccinated or not.
This means that vaccines will likely take longer to reduce transmission and enhance herd immunity than if these new variants had never emerged.
How long this process will last will be the result of a balance between the efficacy of the vaccines against emerging strains and how transmissible and infectious the new strains are.
* By Deborah Fuller, professor of microbiology at the University of Washington School of Medicine. The original article was published in
The Conversation
.
Look also
If I already had Covid-19, do I have to get vaccinated?
and answers to other frequently asked questions
Coronavirus: when will herd immunity be achieved?
