Two years in a pandemic, a mutated version of the Omicron variant, known as BA.2, has been the latest challenge to tame Covid-19.
Subvarians, detected in at least 57 countries, seems to spread even easier than the original.
But so far it does not seem to cause more severe diseases and booster shots remain an effective shield.
Scientists raced to answer a number of questions about this variant when they prepared for the next.
How ruling is BA.2? Omicron is more contagious than Delta, a variant that became dominant globally in the middle of last year, and the new subvarian was very contagious.
Take Denmark, where BA2 has quickly obtained the ground.
A study based on around 8,500 households in December and January found that people infected with Ba.2 spread the virus to an average of 39% of vulnerable household members, a 29% variant for the original Omicron variant.
It is in line with the UK data preliminary.
Is BA.2 more dangerous than Omicron? Omicron and the relevant strains appear less likely than the previous variant to cause serious illness, especially in people who are vaccinated.
The World Health Organization (WHO) said this week that BA.2 seemed no more severe than the original omicron variant, based on evidence from Denmark, where the spread did not cause unexpected nails in hospitalization.
In announcing the final restriction of the Coronavirus late last month, the Danish government stated that this disease no longer pose a threat to the community, even when the case reached the highest record.
How well a vaccine works against it? Data shows some Covid vaccines are less effective in preventing infections caused by omicrons than the previous variants, while still doing good work against severe illness.
Although subvariant seems to be more contagious, Covid shots – especially the booster dose – equally effective with BA.2, according to the initial findings of the British health authority.
25 weeks or more after the second dose, vaccines block 13% of cases that increase to 70% two weeks after the booster.
How is it different from the original? The latest iteration of Coronavirus represents a small portion of infection but has spread rapidly in countries such as South Africa, Denmark, India and England.
Two different versions with around 40 mutations, including the main changes in the Spike BA.2 region.
While both are related, there is enough difference to encourage behavior change.
The lightest form of most cases of omicrons in vaccinated people can make those who recover are still susceptible to existing viruses and future variants, according to researchers.
What does it mean to pandemic? Hunter viruses try to better understand the properties of BA.2 when they are preparing for the future variant, and some believe BA.2 can extend the omicron wave.
The characteristics of the subvarian can lead to “substantial omicron circulation tails,” said Trevor Bedford’s computing biologist from the Fred Hutchinson Cancer Research Center said in Twitter post January 28.
Decline that has the potential to be slower in cases can cause higher hospitalization and cause problems for countries with lower vaccination rates.