- As COVID-19 vaccines continue around the world, many people are still unsure about what vaccines mean for giving them.
- Deborah Fuller, a microbiologist, answers three questions about post-vaccination transmission and whether new changes may affect this.
- The vaccine does not 100% prevent you from becoming infected, but it does reduce your chances of catching it or becoming very ill.
- If the COVID-19 vaccine is caught, the chances of it being delivered are lower, due to a reduction in transmissible viral loads.
So you got your coronavirus vaccine, waited two weeks for your immune system to respond to the picture and they are now fully vaccinated. Does this mean you can make your way through the world like the old days without being afraid to spread the virus? Deborah Fuller is a microbiologist at the University of Washington School of Medicine working on coronavirus vaccines. She explains what science is showing about transmission after the vaccine – and whether new changes could change this equation.
1. Does vaccination completely prevent infection?
The short answer is no. You can still get an infection after you have been vaccinated. But your chances of getting seriously ill are almost zero.
Many people believe that vaccines act as a shield, preventing viruses from completely invading cells. But in most cases, a person who is vaccinated is protected against an infection, which may not be an infection.
Everyone’s immune system is slightly different, so when a vaccine is 95% effective, that just means that 95% of people who get the vaccine will not get sick. These people may be completely immune from infections, or they may be infected but remain asymptomatic because their immune system destroys the virus very quickly. The other 5% of people who have been vaccinated can become infected and become ill, but are very unlikely to be in hospital.
The 100% vaccine does not prevent you from becoming infected, but in all cases it does give your immune system a huge boost on the crown. Whatever the outcome – whether it is complete protection from disease or some stage of the disease – you will be better off after being exposed to the virus than if you had not been vaccinated.
Vaccines prevent disease, not infection.
Image: National Institute of Infectious and Infectious Diseases, CC BY
2. Does disease always mean transmission?
Transmission occurs when enough viral particles from an infected person enter the body of an unprotected person. In theory, anyone with the coronavirus could have it. But vaccinations will reduce the chance of this happening.
In general, if the vaccine does not completely prevent infection, it can significantly reduce the amount of virus coming out of your nose and mouth – a process known as peeling – and shorten the duration. you peeled the virus. This is a big deal. A person who shears less of a virus is less likely to pass it on to someone else.
This seems to be true with coronavirus vaccines. In a recent peer-reviewed study that was not reviewed by peers, Israeli researchers tested 2,897 vaccinated people for signs of coronavirus infection. Most had no identifiable virus, but infected people received a quarter of the virus in their bodies as unvaccinated people who were diagnosed at equal intervals after infection.
Less coronavirus means less chance of being spread, and if the level of virus in your body is low enough, the probability of transmission may be close to zero. However, researchers still do not know where that cutoff for the coronavirus is, and since the vaccines do not provide 100% protection against disease, the Centers for Disease Control and Prevention suggests that people wearing masks and social distance even after receiving the vaccine.
Newer, more infectious and more susceptible variants of the coronavirus may limit the effectiveness of routine vaccines.
Image: AP / John Raoux photo
3. What about the new coronavirus changes?
New variants of coronavirus have emerged in recent months, and recent studies show that vaccines are less effective against certain ones, such as the B1351 variant first identified in South Africa. .
Each time SARS-CoV-2 reproduces, it receives new mutations. In the last few months, researchers have discovered new changes that are more contagious – meaning one has to breathe in less virus to become infectious – and other changes that are more contagious. mobile – means that they increase the amount of virus that a person sheds. And researchers have also discovered at least one new variant that appears to outperform the immune system, according to early data.
So how does this relate to vaccinations and transmission?
For the South African variant, vaccines still provide more than 85% protection from becoming seriously ill with COVID – 19. But when you count moderate and moderate cases, they do not. provides, at best, only about 50% -60% protection. That means that at least 40% of vaccinated people will have a disease strong enough – and enough virus in their body – to cause at least a moderate infection.
If vaccinated people have more viruses in their bodies and pass less of that virus to another person, a person with a vaccine is more likely to be able to get these new strains of the coronavirus.
If all goes well, vaccines will soon reduce the rate of serious disease and death worldwide. To be sure, any vaccine that reduces the level of disease also, at the population level, reduces the amount of virus completely stripped. But due to the emergence of new changes, vaccinated humans still have the ability to shed and spread the coronavirus to other people, vaccinated or otherwise. This means that it is likely to take vaccines much longer to reduce transmission and herd numbers will increase than if these new changes had ever appeared. Just how long this will take is a balance between the effectiveness of vaccines against emerging strains and the transmission and infectivity of these new strains.