Scientists expect the new omicron variants will soon be responsible for most COVID-19 infections, and they will likely cause an increase in re-infection rates.
The SARS-CoV-2 omicron BA.4 and BA.5 subvariants will likely cause an increase in re-infection rates among individuals who have already had COVID, experts say.
Countries from the United Kingdom to Australia have seen an increase in re-infections.
"In the United Kingdom, for example, it is estimated that one in three daily infections are actually re-infections," said Deepti Gurdasani, a clinical epidemiologist at Queen Mary University of London. "That's a high re-infection rate," Gurdasani told DW.
In Australia, the number of people being re-infected with BA.4 and BA.5 has also increased, prompting health officials to revise guidelines for testing after a COVID infection.
The Australian Health Protection Principal Committee (AHPPC), Australia's key decision-making committee for health emergencies, said re-infections may occur as early as 28 days after recovery from a previous COVID infection.
"The AHPPC advises that the reinfection period be reduced from 12 weeks to 28 days. People who test positive to COVID-19 more than 28 days after ending isolation due to previous infection should be reported and managed as new cases," AHPPC said in a statement on July 8.
Re-infection should not be underestimated
In most cases, infections from BA.4 and BA.5 are not as severe as earlier variants like delta. This is reflected in the low number of people requiring hospitalization.
Still, re-infection should still not be underestimated.
"There are cases where people develop chronic disease when re-infected, or become severely ill and are hospitalized," Gurdasani said. "It's worth avoiding every single reinfection and not treating them as inevitable."
Do boosters protect against omicron infection?
The protection provided by COVID vaccines or past infection slowly decreases over time as antibody levels drop.
That means no one is fully protected from BA.5 — new infections are possible despite vaccination and/or past infection and occur more frequently than with past variants.
But there have been fewer deaths and hospital admissions. According to experts, this is because many millions of people are vaccinated or have antibodies, making the general immunity of the population higher than at the start of the pandemic.
Nevertheless, the RKI recommends that the elderly and people in risk groups get another their booster vaccine for extra protection.
More infections but less deadly
The COVID vaccines currently available target the variant of the spike protein that was active at the beginning of the pandemic.
However, the virus has evolved and sharpened its ability to evade the antibodies offered by the vaccines.
Despite that, BA.4 and BA.5 appear to be less dangerous. Some experts say that's because the new variants are more likely to infect the upper respiratory tract than the lungs, causing fewer deaths than earlier in the pandemic, when the lungs were more impacted.
Protection against infection with omicron
The period of time between infection and initial symptoms is shorter in omicron variants than in delta — around three days on average.
The protection offered by a basic two-dose vaccine against omicron infection is not optimal, but it still protects against severe cases of illness. A booster vaccine ensures that more antibodies are formed, offering more protection.
Although omicron with its various subtypes is usually much milder than delta, severe symptoms can also occur in rare cases. Additionally, it is not yet clear what long-term consequences an omicron infection can have.