COVID-19 Disease

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Last reviewed
November 5, 2021

COVID-19 Disease 

Since 2019, the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have been closely monitoring the worldwide outbreak of a novel beta coronavirus known as SARS-CoV-2, which is causing the coronavirus disease 2019 (COVID-19) in humans.

The U.S. CDC Advisory Committee on Immunization Practices (ACIP) Dr. Matthew F. Daley reported on September 22, 2021, an updated COVID-19 pandemic overview and impact of vaccinations. 

COVID-19 Reinfection Immunity and Breakthrough Cases

On January 26, 2021, 'the immune systems of more than 95% of people who recovered from COVID-19 had durable memories of the virus up to eight months after infection. However, the study's results circulating antibody titers were not predictive of T cell memory. Thus, simple serological tests for SARS-CoV-2 antibodies do not reflect the richness and durability of immune memory to SARS-CoV-2.' An updated listing of immunity studies is published at this link.

COVID-19 Breakthrough Infections

The U.S. CDC says 'vaccine breakthrough cases are expected. COVID-19 vaccines are effective and critical tools to control the pandemic; however, no vaccine is 100% effective at preventing illness. As a result, some fully vaccinated people will get sick, and some will even be hospitalized or die from COVID-19.'

COVID-19 Disease Symptoms

The CDC announced on March 3, 2020, that a significant portion of individuals infected with the SARS-CoV-2 coronavirus lack symptoms ("asymptomatic") and that even those who eventually develop symptoms ("pre-symptomatic") can transmit the virus to others for several days before showing symptoms. People with COVID-19 have reported a wide range of symptoms that may appear 2-14 days after exposure to the SARS-CoV-2 virus.

On September 2, 2021, the findings of a cross-sectional study published by The Lancet suggest that differences in symptoms occurring with new loss of taste or smell were seen between groups based on SARS-CoV-2 test positivity. Muscle aches, mild difficulty breathing, vomiting, diarrhea, and congestion were associated with a loss of taste or smell. PLOS published a study that found a 'study that indicates negative smells associated with unpleasantness or unease are processed earlier than positive smells and trigger a physical avoidance response.'

A study published by PLOS on September 28, 2021, identified a set of seven symptoms that, when considered together, maximize detection of COVID-19 in the community, including infection with the B.1.1.7 lineage. They were jointly predictive of PCR positivity and appeared to vary only marginally across age groups: loss or change of sense of smell, loss or change of sense of taste, fever, new persistent cough, chills, appetite loss, and muscle aches.

COVID-19 Long Disease

On October 6, 2021, the WHO published a clinical case definition of the post-COVID-19 condition by a Delphi consensus. The post-COVID-19 condition occurs in individuals with a history of probable or confirmed SARS CoV-2 infection, usually three months from the onset of COVID-19, with symptoms lasting for at least two months and cannot be explained by an alternative diagnosis. Common symptoms include fatigue, shortness of breath, cognitive dysfunction, and others and generally impact everyday functioning. Symptoms may be new-onset following initial recovery from an acute COVID-19 episode or persist from the initial illness. Symptoms may also fluctuate or relapse over time.

People at Risk from COVID-19 Disease

COVID-19 is a new disease, and scientists are still learning how it spreads. However, data published by the U.S. CDC indicates people can catch the COVID-19 disease from others who have the SARS-CoV-2 virus. In addition, older people, and those with underlying medical problems such as obesity, high blood pressure, heart problems, or diabetes, are more likely to develop serious illnesses. As of January 31, 2021, the CDC confirmed that most adults hospitalized for COVID-19 were older, obese, and had comorbidities such as hypertension, cardiovascular, diabetes, and metabolic diseases. 

On March 8, 2021, and October 6, 2020, the CDC stated, 'Obesity increases the risk for severe COVID-19–associated illness. In addition, obesity was a risk factor for hospitalization and death, particularly among adults aged <65 years. These findings highlight clinical and public health implications of higher BMIs, including the need for intensive management of COVID-19–associated illness, continued vaccine prioritization and masking, and policies to support healthy behaviors.' A genetic study published on March 4, 2021, suggests that the risk for COVID-19 hospitalization rises by about 5%-10% per kg/m2 increase in BMI. The evidence linking obesity to adverse COVID-19 outcomes is "overwhelmingly clear," U.K. experts stated on August 10, 2021.

COVID-19 Preventive Vaccines

The COVID-19 vaccine development landscape includes various innovative platforms, says the U.S. FDA. To review a listing of experimental COVID-19 vaccines worldwide, please visit this CoronavirusToday webpage.

Coronavirus FAQs

Note: Content sourced from the CDC, WHO, various governments, news agencies, social media networks, and the Precision Vax news network. All of the posts have been reviewed by medical professionals, such as Dr. Robert Carlson.