This week represented a landmark event in the COVID-19 pandemic: the major epidemiological metrics together were at their lowest points in the U.S. since the pandemic began three years ago. The weekly total cases fell to 77,294, weekly deaths were 1,109, death rate was 0.33 per 100,000, and weekly new hospital admissions were down to 8,060 (note, however, that Florida and Iowa no longer report COVID case numbers and deaths). The CDC announced that it will stop reporting COVID case numbers, vaccine mandates are disappearing, people are shedding their masks, and it almost seems like life is getting back to normal again. But just because the numbers are improving does not mean that everyone is equally safe.
The epidemiological impact of an infection depends on two factors: (1) its incidence and (2) its fatality rate. Take an infection that has a high incidence but low fatality rate, such as rhinovirus. Prior to the COVID pandemic, the average American adult had 2-3 upper respiratory infections per year and the average child had 8-10 URIs per year. Rhinovirus infections account for about one-third of common colds. The net result is that most Americans have at least one rhinovirus infection every year. Rhinovirus causes rather mild symptoms but rarely causes death. On the other end of the epidemiological impact spectrum is ebola, a viral infection that has a low incidence but has a very high case fatality rate. Ebola is rare outside of Western Africa but if someone gets infected, there is a fifty-fifty chance that they will die and a 100% chance that they will at least get very, very sick. Despite its frequency, we really don’t worry too much about rhinovirus infections but even just one case of ebola in the community can induce widespread panic.
The incidence and fatality rate of COVID-19 falls in-between rhinovirus and ebola. Data from the Nationwide Antibody Seroprevalence Survey indicate that by February 2022, approximately 57% of Americans had been infected by COVID-19, a very high incidence but not as high as rhinovirus. The case fatality rate of COVID-19 is somewhere between 0.5% and 1.0% (the exact number is uncertain due to many infections being asymptomatic). This fatality rate is much higher than rhinovirus but much lower than ebola. Consequently, the degree that we worry when COVID-19 cases are in the community is more than rhinovirus but less than ebola.
The UK Biobank Registry study
However, COVID-19 does not affect all people the same. Since the beginning of the pandemic, it has been clear that age has a huge impact on the mortality rate and the older a person is, the more likely they are to die from an infection. A study from this week’s JAMA confirmed the importance of another risk factor for COVID mortality, namely obesity. The study involved 500,000 people from the general population of the United Kingdom who were enrolled in the UK Biobank registry between 2006 – 2010. People with underlying chronic respiratory disease were excluded from the study. Investigators interrogated the UK national electronic health records for data involving COVID infections, lower respiratory infections, and upper respiratory infections in people in the registry between initial enrollment and February 2021. Subjects were divided into four groups based on body mass index (BMI):
- BMI 14 – 24.9 (normal)
- BMI 25 – 29.9 (overweight)
- BMI 30 – 34.9 (obese)
- BMI 35 – 60 (morbidly obese)
The results showed that in the first year of the pandemic (February 2020 – February 2021), overweight individuals were twice as likely to be hospitalized or die of COVID-19 than those with a normal body mass index. Obese individual were three times more likely to be hospitalized or die and morbidly obese individuals were 4 times more likely to be hospitalized or die. When adjusted for subjects’ age, the increased risks for each BMI category were similar.
The study also looked at non-COVID lower respiratory infections (eg, pneumonia and influenza) and upper respiratory tract infections (eg, common colds) over the entire duration of the registry (average = 11.8 years). The results showed that weight was also a risk for severe infection from colds and pneumonia. During the study period, 2.6% of normal weight individuals were hospitalized or died of lower respiratory infection whereas 3.0% of overweight, 4.1% of obese, and 5.6% of morbidly obese individuals were hospitalized or died. The numbers were similar for upper respiratory infections: 0.22% of normal weight, 0.28% of overweight, 0.32% of obese, and 0.44% of morbidly obese individuals were hospitalized or died of upper respiratory infections.
What does all of this mean for healthcare providers?
The implications of the UK Biobank study is that the degree that we relax COVID precautions depends on how likely you are to become severely ill or die if you get a COVID infection. If you are young, healthy, and have a BMI less than 25, then for all practical purposes, the COVID pandemic is over for you and it is reasonably safe to return to life as usual. However, if you have risk factors such as being overweight or obese, then you should still take precautions because even though the incidence of COVID-19 is dropping, if you are unlucky enough to become infected, then you have a higher chance of dying from it. And the higher the BMI, the greater the risk of dying. In the epidemiological impact spectrum with rhinovirus at one extreme and ebola at the other extreme, being overweight or obese pushes COVID-19 more toward the ebola end of the spectrum than being of normal weight.
So, what should we be telling our overweight and obese patients to do? First, vaccinate. Strongly advise unvaccinated overweight persons to get their initial 2-dose COVID series and be sure that those who are vaccinated are advised to get an updated booster. People who live in the same household as an overweight person should similarly be vaccinated to help prevent transmission to those who are overweight. Given the UK Biobank study results for upper and lower respiratory tract infections, overweight and obese patients should also be strongly advised to get pneumococcal vaccines, influenza vaccines (in the fall), and the new RSV vaccine (for those over age 60). Second, advise obese patients to continue to wear masks in crowded indoor areas. Third, continue to make telemedicine available to those patients who are worried about coming into our offices and clinics.
In 1973, Yogi Berra said of the National League pennant race: “It ain’t over ’til it’s over”. For overweight and obese people, the COVID-19 pandemic is not yet over. There are other people for whom the pandemic is also not over. Those who are over age 65 are 97-times more likely to die of a COVID infection than young adults in their 20’s. Chronic diseases that increase the risk of death from COVID include diabetes, heart disease, COPD, immune suppression, kidney failure, cirrhosis, and HIV. Pregnant people are also at increased risk of serious COVID infection. For these people, masks in high-risk settings are still appropriate.
One of the biggest barriers to mask-wearing is the social pressure to stop wearing them. The awkwardness of wearing a mask when no one else around you is wearing one poses a barrier to those people with obesity and other risks for severe COVID who feel self-conscious wearing masks. As physicians, we can normalize mask wearing by our at-risk patients by wearing a mask ourselves in healthcare settings. Most U.S. hospitals have relaxed mask requirements for healthcare workers, patients, and visitors. Because of this, many physicians and nurses have altogether stopped wearing masks in hospitals or outpatient clinics because they are no longer required to. But the reason we should continue to wear masks in these areas is not because of a lower risk that we will get infected ourselves, it is to signal that it is OK to still wear a mask for our patients with COVID risks such as obesity.
Pandemics don’t just all of a sudden stop one day. Instead, they slowly wind down and then fade away. There will come a time when the COVID pandemic is finally over for all of us but we are not there quite yet. Even though the U.S. hospitalization and death rate is now the lowest in three years, we still had more than 8,000 new COVID hospital admissions and more than 1,000 COVID deaths last week in our country. Just because the pandemic seems over for us individually doesn’t mean that it is over for our patients with risk factors such as obesity.
May 6, 2023