Covid-19 has been trending in the news, with several countries announcing an increase in cases and US President Joe Biden testing positive for SARS-CoV-2. Several of my own patients have also tested positive for the virus. The latest variant, KP.3, seems to be taking over and is driving a resurgence in cases. Should we be worried, and what can we do to protect ourselves and our loved ones?
The most recent iteration of SARS-CoV-2 is still part of the Omicron variant of concern (VOC) sublineage and has been designated a variant under monitoring (VUM) by the World Health Organization (WHO). KP.3 and its sublineage KP.3.1.1 are currently responsible for more than half of the cases in the US. It is reportedly gaining ground in Japan where it is also fueling a rise in cases. Fortunately, most of the Covid-19 cases in the United States and Japan continue to be mild, especially among those who were previously vaccinated.
KP.3 does not seem to be any worse than previous variants and its signs and symptoms aren’t much different compared to other SARS-CoV-2 lineages. It does seem to have better immune evasion properties leading to decreased protection against infection for the older vaccines. However, the older vaccines continue to significantly protect against severe disease from KP.3. SARS-CoV-2 is now circulating along with influenza and respiratory syncytial virus and can co-infect patients as well. New rapid tests are available which test for all three viruses at the same time and can help differentiate these in patients with respiratory symptoms. While fewer and fewer people are opting for Covid-19 testing, it is still important for those who may benefit from antiviral treatment.
Most people infected with SARS-CoV-2 who are asymptomatic or only have mild symptoms of Covid-19 will not require antiviral treatment. Rest and supportive care are recommended for faster recovery, and isolation can be discontinued once the patient has been afebrile for at least 24 hours.
People who are at high risk for hospitalization may benefit from antiviral treatment. These include the elderly population above 65 years old, as well as those who have significant comorbid conditions like heart disease, diabetes, or lung disease. The drug of choice for decreasing the risk of hospitalization in these at-risk populations is nirmatrelvir-ritonavir, also known as Paxlovid. Paxlovid, should be taken within five days of the start of symptoms, twice a day by mouth for five days. Remdesivir can also be used for decreasing the risk of severe disease and can be started up to seven days from the start of symptoms. Unfortunately, remdesivir is only available for intravenous use and needs to be given under strict medical supervision. It is given for three days when used for this purpose. Molnupiravir is much less effective than Paxlovid or remdesivir, but can be given to decrease the risk of severe disease if neither drug is available. Similar to Paxlovid, it should be started within five days of symptoms and is given every 12 hours by mouth for five days. Do not take any antivirals for Covid-19 unless specifically instructed to do so by your doctor.
Hospitalized patients are much more complicated to manage than outpatients and the drugs we use, aside from antivirals, can include immunomodulators such as steroids and monoclonal antibodies. Combinations of these drugs can be used depending on the level of oxygen needed and the mode of respiratory support. Severe Covid-19 can still be fatal or result in a prolonged hospitalization, so early recognition of Covid-19 and timely intervention in the at-risk populations is essential to prevent a bad outcome.
What about vaccination? Are our vaccines still any good? The US Centers for Disease Control continues to recommend updated vaccines for people 6 months and older due to concerns about decreased protection from infection. The data still shows that previous vaccination continues to protect against severe disease, and so this recommendation is not echoed by the WHO. WHO does recommend primary vaccination for those who have not received any vaccines, and the newer vaccines should be used if available. Updated vaccines are available from Pfizer, Moderna, and Novavax but none of those have so far made it to the Philippines. If these vaccines do get to our shores, I believe that the most benefit will be for boosting the vulnerable population and for primary vaccination of those who were too young to qualify for the primary series.
Is there a chance that a new and deadly variant of SARS-CoV-2 that escapes the protection of vaccines against severe disease will evolve? This is always a possibility since the virus continues to evolve, but it is unlikely given the persistent circulation of different variants in the community. Ongoing infection in a portion of the population continues to boost immunity against the newer variants, particularly among those who are fully vaccinated. This resulting hybrid immunity has been shown to be much more potent than purely natural or vaccine-mediated immunity. Moreover, widely available diagnostics allow early recognition and mitigation of Covid-19 infection, which can then be treated with antivirals as appropriate. Finally, vigilant surveillance by the health departments of each country and WHO are carefully tracking the evolution of new variants and can quickly flag unusual spikes in mortality and morbidity.
In the meantime, newer treatments are being tested and undergoing clinical trials. Thankfully, there is currently little resistance to our antivirals. As with most rapidly evolving microorganisms, development of resistance is not a question of whether it will happen but when it will happen. Hopefully we will have even more options in our armamentarium when that time comes. The lessons we have learned during the pandemic should also be carried over to other pathogens with pandemic potential, particularly influenza which is on the rise. Last but certainly not the least, nonpharmacologic interventions remain potent weapons that can be quickly deployed regardless of variant or strain of virus. These include the ever-reliable surgical mask which should still be used by the vulnerable population when cases are high, as well as standard measures such as appropriate isolation that can help arrest the spread of infection. As long as we continue to treat COVID-19 with appropriate vigilance, its potential public health risk will remain low for the foreseeable future.