The Omicron Covid variant superseded the previous Delta variant to become the dominant strain late last year. Its ascendency owes in part to its ability to evade some of the attention of vaccine-induced antibodies. Although fears of surging hospital rates have not been realised, a new study does throw cold water on the benefits of getting a booster dose.
Among people who were previously infected with Covid, a third dose of an mRNA vaccine from Pfizer or Moderna may not boost their protection against the Omicron variant of the virus, the new data suggests.
Researchers studied nearly 130,000 people tested for Covid in Connecticut from November 2021 through January 2022, including 10,676 with Omicron infections.
Roughly six percent to eight percent had been infected with previous versions of the coronavirus, according to a report posted on medRxiv ahead of peer review.
Two doses of an mRNA vaccine did help protect against Omicron among people with prior infections, but “we did not detect an additional benefit of receiving a third booster dose among this population,” said Margaret Lind of Yale University.
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A separate study from Canada, also posted on medRxiv ahead of peer review, also echoes these findings.
The research found that more than two vaccine doses “may be of marginal incremental value” for protecting previously-infected individuals against Omicron.
The message, Ms Lind said, “should be that (1) people should get two doses of mRNA vaccine regardless of if they have had a prior infection or not, that (2) people without prior infections should get a booster dose and that (3) people with prior infections should consider a booster dose, especially if they are in a high risk group for life threatening complications, but recognise that it may not provide significant additional protection against infection above two doses.”
So, what are the symptoms of Omicron in the fully vaccinated?
Findings published in infectious disease and epidemiology journal, Eurosurveillance, identified eight symptoms of Omicron in the fully vaccinated.
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It is important to note that “fully vaccinated” meant two doses of an mRNA vaccine at the time.
Researchers in Norway conducted a study interviewing 111 out of 117 guests from a party on 26 November 2021 where there was an Omicron outbreak.
Of the group interviewed, 66 had definitive cases of COVID-19 and 15 had possible cases of the virus.
Of the 111 participants, 89 percent had received two doses of an mRNA vaccine and none had received a booster shot.
The study identified eight key symptoms experienced by the group of fully vaccinated revellers.
These were cough, runny nose, fatigue, sore throat, headache, muscle pain, fever and sneezing.
The study found that cough, runny nose and fatigue were among the most common symptoms in the vaccinated individuals while sneezing and fever were least common.
Professor Tim Spector, lead scientist on the ZOE Covid Study app, has consistently called on the fully vaccinated to look out for “cold-like” symptoms.
The ZOE Covid Study app draws on symptomatic data from millions of users to its app.
The NHS has also updated its list of official of Covid symptoms to now include:
- A high temperature or shivering (chills) – a high temperature means you feel hot to touch on your chest or back (you do not need to measure your temperature)
- A new, continuous cough – this means coughing a lot for more than an hour, or three or more coughing episodes in 24 hours
- A loss or change to your sense of smell or taste
- Shortness of breath
- Feeling tired or exhausted
- An aching body
- A headache
- A sore throat
- A blocked or runny nose
- Loss of appetite
- Feeling sick or being sick.
“Try to stay at home and avoid contact with other people if you get symptoms of coronavirus (COVID-19) again,” adds the health body.