Washington: People who contract Covid-19 even after vaccination tends to have a lower viral load or quantity, experience a shorter infection time and has a symptom that is lighter than individuals who are not vaccinated, according to a MRNA prevention study in the US.
The researchers noted that while the Covid-19 vaccine proved to be very effective in preventing infection, there was no 100 percent effective vaccine, and breakthrough infection – infection after immunization – occurred.
“If you are vaccinated, around 90 percent of the time you will not get Covid-19,” said Jeff Burgess, a professor at the University of Arizona Health Sciences in the US.
“Even if you get it, there will be a little virus inside you and your disease tends to be much lighter,” Burgess said.
This study, published in the New England Journal of Medicine on June 30, involved 3,975 health care workers, first respondents, and important workers and other front lines in the US.
From December 14, 2020, until April 10, 2021, the participants completed the Weekly Test of SARS-COV-2 by providing a nose swab for qualitative and quantitative RT-PCR analysis, gold standard for testing for Covid-19.
Among the participants, SARS-COV-2 infection was identified in five participants who were entirely vaccinated and 11 were partially vaccinated, and in 156 participants who were not vaccinated.
This study found that participants were partially or fully vaccinated with the Pfizer RNA vaccine and Messenger Moderna at the time of infection had a viral load which was less than 40 percent of the participants who were not vaccinated.
The MRNA vaccine uses a molecule called Messenger RNA (or MRNA), rather than the actual pathogen to train the immune system to fight infection.
Viral Load – The number of SARS-COV-2 viruses found in the test sample – not an indicator of how contagious someone, even though initial research shows that it can play a role in the severity of disease and secondary transmission.
The researchers also found that the majority of infections among non-vaccinated participants were detected for two weeks or more, compared to only one week among vaccinated participants.
It represents a 66 percent reduction in the risk that vaccinated people will have an infection that is confirmed for more than one week, they said.
Also, the risk of having Covid-19 with accompanying fever is 58 percent lower for vaccinated participants, according to research.
They reported two days less pain in bed, on average, and the length of the overall disease was six days shorter than people who were not vaccinated, the researchers said.
The study found that two doses of MRNA Covid-19 vaccine were 91 percent effective against infection with SARS-COV-2, the virus which caused Covid-19.
On the other hand, a single dose of vaccine proved to be 81 percent effective against SARS-COV-2 infection, the researcher said.
This is equivalent to study data published in the US Disease Control Center and Morbidity and Weekly Mortality Morbidity on March 29, this year.
“We still see a high level of effectiveness of vaccines, so we feel good about it,” Burgess said.
“But more importantly, we have added a number of sizes of infection severity among individuals who have been vaccinated as comparisons with those who have not yet, and we measure how many viruses are there and how long,” he added.