The Omicron variant spreads easier than other variants of coronavirus. Reinfection is possible even if a person has already had this virus or is fully vaccinated.
Several factors can influence reinfection, such as age, geographic location, and health equity.
This article discusses current research regarding Omicron and other coronavirus variants, risk factors for reinfection, symptoms to watch for, and preventive measures people can take against reinfection.
Omicron is a variant of SARS-CoV-2, the virus that causes COVID-19. The Network for Genomics Surveillance (NGS) in South Africa first reported it to the
According to the Our World in Data COVID-19 database, the number of confirmed Omicron cases reported between December 2021 and March 2022 exceeded all previously reported cases.
Symptoms of COVID-19 due to the Omicron variant are
Another difficulty in detecting this variant is the S gene, a predominant feature of the Omicron variant. In 2021,
The distinguishing marker of the Omicron variant is its spike protein, which contains 26 amino acid mutations. This
As scientists have only studied a
Like all virus variants, Omicron comprises several lineages and sub-lineages. A lineage is a group of closely related viruses with a common ancestor. In this case, it is SARS-CoV-2.
Omicron’s original lineage is
There have been several variants of concern since the original outbreak of COVID-19. These include:
Beta variant (B.1.351)
The Beta variant first appeared in South Africa in
The Centers for Disease Control and Prevention (CDC) state that the Beta variant is about
Primary vaccinations were
The Alpha variant (B.1.1.7)
The Alpha variant is
Infections surged in December 2020, and Alpha soon spread around the world, becoming the dominant variant in the U.S. According to the CDC, the Alpha variant accounted for
The Delta variant (B.1.617.2)
The Delta variant first appeared in India in
The Delta variant accounted for more than 99% of COVID-19 cases and led to an increase in hospitalizations. Unvaccinated people were at high risk of contracting the Delta variant.
Research states that vaccination is the best protection against the Delta variant.
The Gamma variant (B.188.8.131.52 or P.1)
The Gamma variant first appeared in Brazil in
However, it was less transmissible than the Alpha and Delta variants. Studies show that vaccinations are less effective against the Gamma variant than the Beta variant.
BA.4 and BA.5 sublineages
Scientists first detected these lineages in
These two lineages started the fifth wave of COVID in South Africa and accounted for 50% of cases.
The BA.4 and BA.5 lineages have an advanced growth rate due to the relative ineffectiveness of vaccinations. More research is necessary to see if these lineages will cause hospitalization.
Omicron sublineage BA.2
The Omicron sublineage BA.2 first appeared in March 2022. The
This variant is currently the world’s most dominant variant and has a growth advantage over BA.1.
However, the BA.2 variant is less likely to reinfect those who have already contracted the BA.1 variant.
The following table summarises how effective the vaccines available in the U.S. are at preventing infection from certain SARS-CoV-2 strains, according to the CDC.
|Vaccine||Effectiveness against infection|
|mRNA overall||• 58% without prior infection|
|Pfizer-BioNTech||• 67%, around 150 days after the second dose, pre-Delta|
• 33%, around 150 days after the second dose, during Delta
|Moderna||• 75%, around 150 days after the second dose, pre-Delta|
• 77%, around 150 days after the second dose, during Delta
|Janssen||• up to 17.8%, 2 weeks to 4 months after the last dose, during Omicron|
• up to 29.2%, 2 weeks to 4 months after the last dose, during Omicron
|Janssen/mRNA||• up to 61.3%, 2 weeks to 1 month after the last dose, during Omicron|
- Age: Older adults are more likely to get very sick from COVID-19.
- Geographic factors: Some people are more at risk of contracting the virus because of where they live or work or because they cannot easily access healthcare.
- Health equity: This includes discrimination and racism toward people from ethnic minority groups and education, income, and wealth disparity.
- Previous infection of COVID-19: According to the
WHO, evidence suggests that reinfection from the Omicron variant may be higher in people who have previously had COVID-19.
- chronic kidney disease
- chronic lung diseases
- cystic fibrosis
- dementia or other neurological conditions
- diabetes (type 1 or 2)
- heart conditions or stroke
- mental health conditions, such as mood disorders, depression, and schizophrenia
- being immunocompromised or having a weakened immune system
- physical inactivity
- hemoglobin blood disorders
- blood stem cell transplants, such as bone marrow transplants
- substance use disorders
The symptoms of Omicron are
- changes in the sense of taste and smell
- shortness of breath
- fatigue and weakness
- sore throat
Certain factors can affect the severity and duration of the Omicron variant, such as underlying health conditions, age, and history of prior infection.
People can help stop the spread of the Omicron variant — and protect themselves and others — by taking the following preventive actions:
- getting vaccinated
- improving ventilation
- getting tested if symptoms are present
government recommendationson how to manage personal exposure
- avoiding contact with people who have a suspected variant
- wearing a mask in public indoor spaces
- socially distancing where possible
It is possible to contract Omicron twice. Many factors can influence reinfection risk, such as age, geographic location, and health equity.
Omicron is one of several variants of concern. Vaccination is more or less effective against different strains of COVID-19.
However, people should still receive their vaccinations and take further preventive actions such as wearing masks where possible and socially distancing. It is essential to follow all public health advice to reduce the risk of reinfection.