The paired and replicated chromosomes are called bivalents or tetrads, which have two chromosomes and four chromatids, with one chromosome coming from each parent.
In the early 2000s, vaccines known as bivalent oral vaccines were developed to target only PV1 and PV3 because of the drop in circulation of the PV2 strain.
科学快报-科学美国人Science Quickly, from SCIENTIFIC AMERICAN
This is because the federal government has purchased nearly two billion doses of COVID vaccines and 171 million bivalent boosters—the ones formulated to cover Omicron strains.
The administration, they've had to borrow, beg and steal money from different programmes to actually be able to purchase the new bivalent boosters from Pfizer and Moderna.
政府, 他们不得不从不同项目中借钱、乞讨和窃取资金, 才能真正从辉瑞和 Moderna 购买新助推器。
The new bivalent booster protects you against both the original SARS-CoV-2 strain and Omicron's BA. 4 and BA. 5 subvariants, and it's likely to provide some protection against the newer variants too.
The autumn Covid-19 booster shots we have just been offered are one such example – these bivalent vaccines target the original strain of Sars-CoV-2 (the virus that causes Covid-19) alongside the Omicron variant.
So right now, if you're asking a clear question, of today, with the bivalent BA.4-5 boosters or updated vaccines is a better terminology to use, they are available now throughout the country.
Just 15% of people in the U.S. ages 5 and older have gotten a bivalent booster, according to the CDC, which means many people are currently not as protected as they could be against the new variant.