All pandemics continue for a few years, or even longer, in one form or another. The past two winters of COVID-19 were challenging and met with vigor. But the Northern Hemisphere is particularly vulnerable ahead of a new winter season, just as the Global South was during its cold season. The COVID-19 pandemic, which is still ongoing, is now in its multiple mutation stage. This fact means that case numbers will increase over the winter season and prevention measures may have to be reintroduced for those who are inclined and able. There are more than 300 omicron subvariants currently being tracked by the World Health Organization to gauge what turn the pandemic may take as we enter winter 2022. According to research, omicron has seen its lineages, such as BA.1, BA.2 and BA.4/BA.5, cause distinct waves. Currently, five sub-mutations of these lineages have acquired growth advantages that are driving up cases. The new front runners are BQ.1.1, BA.2.3.20, BQ.1, BA.2.75.2 and XXB. Even among these, there are geographic heterogeneities making cases unique. The BQ.1 and BQ.1.1 subvariants emerged over the past month. There are new concerns among health practitioners that countries need to brace for another potential winter surge, particularly in Europe and North America. The new subvariants are steadily spreading. With the omicron subvariant BA.5 beginning to decline, these newer mutations have begun to rise in what some term a battle for disease dominance. In the US, the shift in variant dominance is ongoing. Both BQ.1 and BQ.1.1 descend from BA.5, an omicron subvariant that currently accounts for about 68 percent of COVID-19 cases in the country. Research shows that BA.5’s relatives are quickly gaining ground. BQ.1 and BQ.1.1 each accounted for 5.7 percent of new COVID-19 cases during the week ending Oct. 15. In comparison, in the UK, infections from the highly mutated subvariant BQ.1.1 are doubling every week — a rate of growth that far exceeds other leading subvariants. Back in the US, BQ.1.1 is spreading twice as fast as its cousin, BA.2.75.2. In fact, BQ.1.1 seems to be the first form of COVID-19 against which antibody therapies do not work at all. There are new concerns among health practitioners that countries need to brace for another potential COVID-19 surge Dr. Theodore Karasik East Asia is also not immune to new infections from mutation. A new subvariant called XBB began spreading in Singapore, doubling in a day early last week. The same subvariant has also appeared in Hong Kong. XBB is a highly mutated descendant of the omicron variant that drove a record wave of infections last winter. It is more contagious than any previous variant and, like BQ.1.1, it evades the antibodies from monoclonal therapies. It is unclear whether the newest batch of bivalent booster shots will work against the XBB variant. A few weeks ago, all these variants barely showed up on the Centers for Disease Control and Prevention’s disease tracker or in British or other healthcare systems, which suggests they are able to spread fast now that the winter season is approaching. The problem with mutations is the ability to respond appropriately so there is no threat to the immune system’s response. One virologist said: “This is essentially viral evolution on steroids.” By New Year’s Day, the disease landscape may be quite interesting indeed. Vaccines and boosters are the best tools we have, but the emergence of the BQ variants is further proof that even they are not enough to fully shield people from sickness. Health professionals are arguing that, if an evasive variant like BQ.1 or BQ.1.1 spreads widely this winter and some lines of defense are rendered less effective, other precautions such as the wearing of face masks and avoiding crowded indoor areas may once again be necessary to protect against infection. The way the virus is evolving now is unlike what we had seen up until last year, when the omicron variant was first detected in South Africa. There were no preexisting immunity factors. Some of these issues were solved with booster programs, but there may now be a real requirement to go into another cycle of prevention. The idea is to get ahead of the antigenic drift ongoing in the omicron sub-mutations and variants. We know that this winter wave is coming so, again, being proactive is key. Health systems know to prepare using the lessons learned of 2020 and 2021. The same rules apply as individuals exercise their freedom of choice in whether or not to get a booster. But what is harder to predict is the effect on hospitalizations during the coming wave. Scientists argue that the buildup of immunity in the population thanks to vaccinations and previous infections is likely to keep hospital admissions lower than during past waves, which is good news. The only remaining worry is that influenza, which has barely registered over the past two winters, is likely to come back in the Northern Hemisphere this season, creating concern about what scientists are calling a “twindemic” of influenza and COVID-19. More health and treatment challenges lie ahead. • Dr. Theodore Karasik is a senior adviser to Gulf State Analytics in Washington. Twitter: @tkarasik