Tuberculosis, the flu, and COVID-19 differ in disease prevalence and burden, requiring different public health responses

CLAIM
“Why don’t we wear masks for [tuberculosis]? Because CNN hasn’t instructed you to.”
DETAILS
Misleading: Although the statistics related to tuberculosis (TB) and flu in these posts are generally accurate, there are effective vaccines and treatments available for these diseases, unlike COVID-19. Furthermore, the prevalence of TB in the U.S. is substantially lower than COVID-19, and the seasonal flu has a much lower mortality rate than COVID-19. Together, these factors explain why public health responses to COVID-19, TB, and the seasonal flu differ.
KEY TAKE AWAY
COVID-19, tuberculosis (TB), and the flu are all respiratory illnesses that spread through the air, hence protective measures recommended for these diseases are similar. However, the three diseases differ in disease prevalence and burden, leading public health officials to devise recommendations specific to each disease. Unlike TB and the flu, there are no effective treatments or vaccines for COVID-19. The number of TB cases in the U.S. is extremely low, and the flu has a lower mortality rate than COVID-19. These factors taken together explain why public health measures for controlling COVID-19 spread are needed in the community, but not implemented in the case of TB and the seasonal flu.

FULL CLAIM: “Last year alone, 10 million fell ill from TB and 1.5 million died. Nearly one quarter of the world's population (1.8 billion people) are infected with Mycobacterium tuberculosis, the bacteria that causes TB. Why don’t we wear masks for TB? Because CNN hasn’t instructed you to”; “The flu killed 665,000 people worldwide last year. You weren’t scared of it because the media didn’t tell you to be.”

REVIEW


Claims that the COVID-19 pandemic response is an overreaction because the same measures aren’t being applied to tuberculosis (TB) and other diseases like the flu have circulated online since at least April 2020. These claims continue to propagate on Facebook as recently as August and September 2020 (see examples here and here), receiving more than 64,000 shares. Some of these posts cite statistics from the World Health Organization (WHO), stating that “TB is the leading infectious cause of death worldwide” and questioning why masks aren’t being worn to reduce the spread of TB. Other posts claim that “The flu killed 665,000 people worldwide last year. You weren’t scared of it because the media didn’t tell you to be.”

TB is caused by the bacterium Mycobacterium tuberculosis, while COVID-19 and the flu are caused by viruses. All three are respiratory illnesses that are spread in the air, hence the protective measures recommended for these diseases are highly similar. These measures include physical distancing and frequent handwashing. In the case of TB and COVID-19, protective measures also include the use of face masks. According to the International Union Against Tuberculosis and Lung Disease:

Masks have been used in TB infection prevention and control for many years to reduce the risk of further spread of TB. Personal protective equipment (PPE), such as surgical face masks and respirators, are only a part of TB infection control and prevention measures. […] For TB, as there is an effective treatment available, once a person is on the right treatment the risk of infecting others rapidly decreases and there is often no need to wear a mask. It follows that the earlier people with TB are diagnosed and started on correct treatment, the better; these steps are crucial in interrupting spread of TB pathogens in our families and communities.

Although there are similarities between the three diseases and the statistics listed in these posts are generally accurate, there are substantial differences between these diseases that also influence which public health measures are recommended. These posts have omitted mentioning these differences, which would explain why the public health response to TB and the seasonal flu differs from the response to COVID-19.

One important difference that sets both TB and the flu apart from COVID-19 is that TB and flu have been known and In contrast to COVID-19, TB and flu were identified decades ago and are far better understood by scientists and public health officials. This knowledge enabled scientists to effective drugs for treating TB and reducing the severity of the flu. Furthermore, vaccines are available that can prevent TB and the flu.

In contrast, COVID-19 emerged less than a year ago at the end of 2019. To date, there are no effective drugs for treating the disease nor is there a vaccine that has demonstrated efficacy in preventing the disease. Clinical trials for evaluating the efficacy of various drugs, like the WHO’s Solidarity trial, and vaccines are currently underway.

The disease burden of COVID-19 is also different from that of the seasonal flu and TB. COVID-19 is circulating in all countries, and the U.S. currently has the highest number of COVID-19 cases in the world. The Coronavirus Resource Center by Johns Hopkins University, there have been more than 6 million cases and nearly 200,000 deaths to date in the U.S. as of 21 September 2020.

While the flu also circulates in all countries, the mortality rate of seasonal flu is lower than that of COVID-19. The estimated infection fatality rate (IFR) of seasonal flu is about 0.04%, which is the mortality rate among all infections, both confirmed and undetected, according to Christophe Fraser, an epidemiologist at Oxford University. Estimates of the IFR of COVID-19 range from 0.5 to 1%, more than ten times that of the seasonal flu. This difference in disease burden is reflected in the U.S. CDC estimates of the flu burden from the 2018-2019 season, where about 35.5 million people fell ill with the flu, resulting in 34,200 deaths. Although the number of flu cases are much higher than that of COVID-19, the number of deaths from the disease are much lower.

TB is distinct from the flu and COVID-19 as its prevalence is unevenly distributed geographically. The WHO states that in 2018, an estimated 10 million people fell ill with TB worldwide. Eight countries—all of which are developing countries—accounted for two-thirds of all TB cases in 2018, including India, China, Indonesia, the Philippines, and Pakistan.

In the U.S., only 9,025 TB cases were reported in 2018 among a population of about 328 million, with 515 deaths attributed to TB in 2017. Furthermore, the case rate in the U.S. has decreased or remained stable for the past decade. This indicates that TB transmission in the community is extremely low. Conversely, the number of COVID-19 cases in the U.S. continues to grow over time, indicating that its transmission in the population is high.

Overall, these claims assert a false equivalence between TB, the flu, and COVID-19 to imply that the public health response to the COVID-19 pandemic is overblown. Although these diseases are all respiratory illnesses that spread through the air, there are important differences in their prevalence and burden. Therefore, the public health response needed for each disease is different. Unlike TB and the flu, there are no effective treatments or vaccines for COVID-19. Furthermore, the number of TB cases in the U.S. is extremely low compared to COVID-19 cases, and the flu has a lower mortality rate compared to COVID-19. These factors altogether explain why widespread public health measures, like physical distancing and use of face masks, are necessary to reduce the spread of COVID-19, but not implemented in the case of TB and the flu.

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These claims have also been fact-checked by Reuters and PolitiFact; Reuters found the claim to be misleading, while PolitiFact rated it Mostly False.

     

Published on: 21 Sep 2020 | Editor:

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