HPI COVID-19 for doctors of optometry: Part I public health background

Health Policy Institute - HPI

PART 1: Public Health and Epidemiology of COVID-19 for Doctors of Optometry

Updated April 28, 2020

The American Optometric Association (AOA) Health Policy Institute (HPI) is providing information relevant to the eye health and vision care community regarding the novel coronavirus (SARS-CoV-2) and COVID-191. Every doctor of optometry should understand the risks associated with this outbreak to ensure continued ability to care for patients.

On Jan. 30, 2020, the World Health Organization (WHO) declared COVID-19 (then known as 2019 nCoV) as a global health emergency. The U.S. Secretary of Health and Human Services (HHS) declared a public health emergency on Jan. 31, 2020, under section 319 of the Public Health Service Act (42 U.S.C. 247d), in response to COVID-19.2

Dr. Tedros Adhanom Ghebreyesus, director general of the WHO reported in March 30, 2020 briefing that the rapidly increasing demand on health facilities and health workers threatens to leave health systems worldwide overstretched and unable to operate effectively. His focused message was that physical distancing measures are necessary to slow the transmission of the virus to aid the health care system and mitigate the risk of systems collapse. Adding, "to suppress and control COVID-19 epidemics, countries must isolate, test, treat and trace. If they don't, transmission chains can continue at a low level, then resurge once physical distancing measures are lifted. Don't assume your community won't be affected. Prepare as if it will be. Don't assume you won't be infected. Prepare as if you will be. But there is hope. There are many things all countries can do." The U.S. Centers for Disease Control and Prevention (CDC) stresses that COVID-19 can result in severe disease, including hospitalization, admission to an intensive care unit, and death, especially among older adults (ages 55 and over) and adults with certain underlying health conditions. Everyone can take actions, such as social distancing and staying home, to help slow the spread of COVID-19 and protect older adults from severe illness.

COVID-19 in the U.S.

According to a April 28, 2020, New York Times data base, 1 million-plus people across every state, plus Washington, D.C., and three U.S. territories, have tested positive for COVID-19, and at least 57,388 patients with the virus have died, which now includes 5,200 in New York City who were believed to have COVID-19 (people who did not have a positive COVID-19 laboratory test, but their death certificate lists as the cause of death "COVID-19" or an equivalent). In recent days, cases and deaths have grown rapidly. In New York state there are more than 295,137 total confirmed cases with 17,683 people dead (with a confirmed diagnosis) and the worst not yet reached. Find nationally where cases are rising the fastest. According to a March 30, 2020, interview with the CDC Director Robert Redfield, M.D., a significant number of individuals who are infected actually remain asymptomatic. Dr. Redfield states, "That may be as many as 25%. That's important, because now you have individuals that may not have any symptoms that can contribute to transmission, and we have learned that in fact they do contribute to transmission." He added, "Of those of us that get symptomatic, it appears that we're shedding significant virus in our oropharyngeal compartment, probably up to 48 hours before we show symptoms. This helps explain how rapidly this virus continues to spread across the country, because we have asymptomatic transmitters, and we have individuals who are transmitting 48 hours before they become symptomatic." This highlights the necessity of current stay-at-home directives in most states. On April 13, 2020, Dr. Thomas Frieden, chief executive at Resolve to Save Lives, an initiative of Vital Strategies to prevent epidemics and cardiovascular disease, and former director of the CDC, said superspreading events may involve people with symptoms that linger but who are not sick enough to stay home.

American adults of all ages—not just those in their 70s, 80s and 90s—are being seriously sickened by the coronavirus. On April 8, 2020, the CDC released Hospitalization Rates and Characteristics of Patients Hospitalized with Laboratory-Confirmed Coronavirus Disease 2019 - COVID-NET, 14 States, March 1-30, 2020.4

Figure 1. Hospitalization rates and characteristics of patients hospitalized with laboratory-confirmed coronavirus disease 2019-COVID-NET, 14 states, March 1-30, 2020.

Figure 1. Hospitalization rates and characteristics of patients hospitalized with laboratory-confirmed coronavirus disease 2019-COVID-NET, 14 states, March 1-30, 2020.

Figure 2. Underlying symptoms among adults aged ≥18 years with coronavirus disease 2019 (COVID-19)—Associated hospitalizations-COVID-NET, 14 states,* March 1-30, 2020. (Adapted by HPI)

Figure 2. Underlying symptoms among adults aged ≥18 years with coronavirus disease 2019 (COVID-19)—Associated hospitalizations-COVID-NET, 14 states,* March 1-30, 2020. (Adapted by HPI)

COVID-19-associated hospitalizations in the United States are highest among older adults, and nearly 90 percent of persons hospitalized have one or more underlying medical conditions. Hospitalization Rates and Characteristics of Patients Hospitalized with Laboratory-Confirmed Coronavirus Disease 2019 - COVID-NET, 14 States, March 1-30, 20205

Figure 3. Underlying conditions among adults aged ≥18 years with coronavirus disease 2019 (COVID-19)-associated hospitalizations-COVID-NET, 14 states,* March 1-30, 2020. (Adapted by HPI)

Figure 3. Underlying conditions among adults aged ≥18 years with coronavirus disease 2019 (COVID-19)-associated hospitalizations-COVID-NET, 14 states,* March 1-30, 2020. (Adapted by HPI)

Apart from the death rate, the secondary attack rate of transmission of a virus is an important number to monitor. This number (R0, pronounced R-nought or r-zero) serves as an indicator of how easy the disease spreads from person-to-person, as indicated by its reproductive number, which represents the average number of people who will catch the disease from a single infected person. An outbreak with a reproductive number of below 1.0 will gradually disappear. As of Feb. 10, 2020, the R0 of COVID-19 has been reported as high as 4.08.6 Preliminary studies had estimated R0 to be between 1.5 and 3.5.7,8,9 Based on these numbers, on average every case of COVID-19 would create three to four new cases.

COVID-19 is of high concern because it is a novel virus, meaning it has never occurred before in humans. It is important to note that the virus is transmitted person-to-person through either direct contact or an exchange of bodily fluids. A new study published in the New England Journal of Medicine on March 17, 2020, found that viable virus could be detected up to three hours later in the air, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

Global concern has escalated due to the rapid spread of the disease internationally including cases identified and presenting in the U.S. The CDC believes at this time that symptoms of COVID-19 may appear in as few as two days or as long as 14 days, with median estimates of five to six days after exposure. Evolving information from the CDC on the outbreak can be found at cdc.gov/coronavirus/2019-ncov/about/index.html.

As discussed above, this information is evolving as public health organizations track and learn more about the spreading COVID-19 coronavirus. It is important to monitor for changes in information from the CDC  and WHO to best protect against infection.  


  1. On Feb. 11,2020 the WHO renamed 2019-nCoV to COVID-19.
  2. whitehouse.gov/presidential-actions/proclamation-declaring-national-emergency-concerning-novel-coronavirus-disease-covid-19-outbreak/
  3. who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---30-march-2020
  4. cdc.gov/mmwr/volumes/69/wr/mm6915e3.htm?s_cid=mm6915e3_e
  5. cdc.gov/mmwr/volumes/69/wr/mm6915e3.htm?s_cid=mm6915e3_e
  6. Estimating the effective reproduction number of the 2019-nCoV in China - Zhidong Cao et al., Jan. 29, 2020
  7. Novel coronavirus 2019-nCoV: early estimation of epidemiological parameters and epidemic prediction - Jonathan M. Read et al, Jan. 23,2020.
  8. Early Transmissibility Assessment of a Novel Coronavirus in Wuhan, China - Maimuna Majumder and Kenneth D. Mandl, Harvard University - Computational Health Informatics Program - Posted: 24 Jan 2020 Last revised: 27 Jan 2020
  9. Report 3: Transmissibility of 2019-nCoV - 25 January 2020 - Imperial College London