The XBB recombinant resulting from BA.2.10.1 and BA.2.75 that emerged in southeast Asia has now appeared in New England states, New Jersey and New York, responsible for five percent of cases investigated.  There is no evidence that this sub-variant is more pathogenic than the BA progenitors but given differences from currently circulating viruses with respect to the receptor-binding domain, XBB may be regarded as an “escape variant”.  According to the National Institute of Allergy and Infectious Diseases, updated boosters should offer some protection against XBB but this will be inferior to circulating sub-variants, including BA.4.

It is inevitable that winter will see an upsurge in COVID attributed to emerging variants.  The clinical disease situation will be complicated by a rising incidence rate of influenza.  A high level of protection against this viral infection can be obtained from receiving the available seasonal  multivalent influenza vaccine together with commonsense hygiene precautions.