The rapid advance of the omicron variant of the coronavirus has health authorities on alert.
On Monday, January 10, the United States reported a record of 1.35 million new infections, the highest daily figure of any country, according to data from the Reuters agency.
On Tuesday, the World Health Organization (WHO) warned that half of the population in Europe it will have been infected with the omicron variant in the next six to eight weeks.
And on Wednesday, the Pan American Health Organization (PAHO) reported that due to omicron, covid-19 infections in America almost they doubled in the last week.
“Infections are accelerating in all corners of the Americas and once again our health systems face challenges“, said Carissa Etienne, the director of PAHO.
At BBC Mundo we explain some aspects of omicron and why experts warn that should not be considered a mild disease which causes this variant.
1. Why is the omicron variant so contagious?
According to epidemiologist Maria Van Kerkhove, WHO technical lead for covid-19, there are three main reasons:
- This variant of the virus developed mutations that allow it to adhere easiermindto human cells.
- We have “escape immunity”. That is, people can be reinfected even if they have had the disease before or have been vaccinated.
- Omicron replicates in the upper respiratory tract, with which it is easier for the virus to spread, unlike the delta and other variants that replicate mostly in the lower respiratory tract; that is, the lungs.
The Covid Vaccine Hub portal indicates that it is difficult to estimate how transmissible omicron is compared to other variants, but that some estimates from the UK Health Security Agency indicate that it may be between two and more of three times more infectionsto than the delta.
The United States Centers for Disease Control and Prevention (CDC) point out that Omicron is “likely” to spread easiermind than the original SARS-CoV-2, but it is “not yet known” how easily it spreads compared to delta.
The CDC indicates that anyone infected with omicron can spread the virus, even if vaccinatedto or have no symptoms.
2. What are the symptoms?
According to the Zoe Covid Symptom Study, led by Tim Spector, an epidemiologist at King’s College London, so far it is known that the most common symptoms of the omicron variant are:
- Runny nose
- Fatigue (mild or severe)
- Throat pain
The National Health Service of the United Kingdom (NHS, for its acronym in English) indicates that we must continue to monitor the classic symptoms of covid:
- Continuous and sudden cough
- Fever or high temperature
- Loss or change in taste and smell
3. Does Omicron cause less severe disease than the delta variant?
The CDC says more data is needed to know if infection with omicron causes less severe or fatal disease compared to other variants.
Some indicators, however, point to the fact that in some cases omicron can cause milder symptoms, but can still cause hospitalization and death, especially in people who are not vaccinated.
On December 31, the UK Health Security Agency published a report showing that people infected with omicron had a third as likely to end up hospitalized compared to those infected with delta.
On the portal of the Department of Public Health Sciences of the University of California Davis, the epidemiologist Lorena García indicates that the symptoms of omicron can be very different between vaccinated and unvaccinated people.
“In those who are fully vaccinated and on booster doses, symptoms tend to be mild. On the contrary, if a person is not vaccinated, the symptoms can be quite serious and cause hospitalization or even death,” says García.
The WHO has warned that omicron it should not be seen as a mild disease.
“Although omicron seems to be less serious Compared to delta, especially in vaccinated people, that doesn’t mean it should be classified as mild,” WHO director Tedros Adhanom Ghebreyesus warned in early January.
“Like previous variants, omicron is causing hospitalizations and killing people.”
4. Do vaccines work against omicron?
People with two doses remain protected against hospitalization, even if they have lost some protection against infection, according to Ignacio López-Goñi, professor of Microbiology at the University of Navarra, Spain, in an article published on December 28. in The Conversation.
A study from MIT and Harvard University published on January 7 indicates that two doses of Pfizer or Moderna “do not produce antibodies capable of recognizing and neutralizing the omicron variant” but that “a booster dosedramatically improves protection against omicron.”
Andrew Lee, professor of public health at the University of Sheffield, England, points out that the data show that two doses of the Pfizer or AstraZeneca vaccines offer limited protection against omicron, but that protection is seen quickly restored with a booster dose, as explained in an article in The Conversation of January 5.
Lee also points out that it is normal that some people inoculated they get infected with omicron, since vaccines are not designed to prevent infection, but to reduce the chance that someone who has been infected will develop serious illness or die.
“Until now, vaccines have proven to be very good at preventing severe disease,” says Lee.
The CDC indicates that “the emergence of omicron emphasizes the importance of getting vaccinated and take the booster dose.”
On January 11, a WHO panel indicated that Covid-19 vaccines may need to be update to ensure they are effective against new variants like omicron.
5. If I have already had covid or have already been vaccinated, is it possible that I could get the omicron variant?
An Imperial College London report dated December 17, still under review, shows that omicron has great ability to evade immunity which grants a previous infection.
The document estimates that the risk of being reinfected with omicron is 5.4 times higher that with delta.
The protection against omicron reinfection provided by a past infection may be as low as 19%, the study indicates.
Regarding vaccines, Dr. Gregory Poland, director of the Vaccine Research Group at the Mayo Clinic in the US, indicates that the protection they offer against omicron goes decaying over time.
“If you get two doses of the vaccine, after at least three months your protection against infection or hospitalization drops to about 30% to 40%,” Poland says on the Mayo Clinic website.
Poland indicates that with the booster dose immunity can be between 75% and 80%.
“Notice I didn’t say 100%,” warns Poland. That’s why we still use masks. That’s why we still keep our distance.”
6. What immunity do I get after overcoming the omicron infection?
“What we knew from previous variants is that people with hybrid immunity (vaccinated + infection) developed a more powerful and lasting immune response than those only vaccinated or only infected,” Salvador Peiró, a specialist in public health and pharmacoepidemiology researcher at FISABIO, a biomedical research foundation in Spain.
Peiró, however, warns that ómicron has been able to infect people who have already had the disease or who have already been vaccinated, at least when some time has passed (more than five or six months) since vaccination or infection.
7. Can I get covid again after having recovered from omicron? Can I get it twice with the omicron variant?
“In theory, yes, although reinfections will be extremely rare in the following months after having overcome the covid”, says Peiró.
Peiró adds that these reinfections will be even rarer in people who, in addition to having overcome covid, have received a third dose of the vaccine.
The expert indicates that due to how recent the infections are, it is not yet known how long and to what extent these reinfections will occur.
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