US health regulators approved the first pill against COVID-19 on Wednesday, which is a Pfizer drug that Americans can take at home to prevent the worst effects of the virus.

The long-awaited milestone comes as the number of cases, hospitalizations and deaths in the United States is on the rise, and health officials have warned that the omicron variant may cause a tsunami of new infections overwhelmed by hospitals.

The drug Paxlovid is a faster and cheaper way to treat early COVID-19 infection, but the initial supply will be very limited. All previously approved drugs for the disease require intravenous injection or injection.

Merck’s antiviral drugs are also expected to be authorized soon. But Pfizer’s drug will almost certainly be the first choice because of its mild side effects and superior efficacy, including a nearly 90% reduction in the hospitalization rate and deaths of patients most likely to develop serious diseases.

“It has high efficacy, low side effects, and it is oral. It checks all the boxes,” said Dr. Gregory Poland of the Mayo Clinic. “You find that the risk of hospitalization and death for high-risk groups is reduced by 90%-this is shocking.”

The US Food and Drug Administration has approved Pfizer’s drugs for adults and children 12 years of age and older who have tested positive for COVID-19 and have early symptoms, and these children are at the highest risk of hospitalization. This includes the elderly and people with diseases such as obesity and heart disease. Children who are eligible to use the drug must weigh at least 88 pounds (40 kg).

Pfizer and Merck’s pills are expected to be effective against omicron because they do not target the spike protein where most of the variant’s worrisome mutations are located.

Pfizer currently offers 180,000 treatment courses worldwide, of which approximately 60,000 to 70,000 are allocated to US federal health officials, and are expected to be shipped to the worst-hit areas of the country in advance. Pfizer said the low supply is due to manufacturing time-currently about 9 months. The company said it could halve production time next year.

The US government has agreed to purchase enough Paxlovid to treat 10 million people. Pfizer said that under contracts with the United Kingdom, Australia and other countries, 80 million courses will be produced globally next year.

Health experts agree that vaccination is still the best way to prevent COVID-19. However, because approximately 40 million American adults are still not vaccinated, effective drugs are essential to contain the current and future wave of infections.

The United States now reports more than 140,000 new infections every day, and federal officials have warned that the omicron variant may cause the number of cases to soar. Federal officials confirmed earlier this week that Omicron has become a major breed nationwide.

In this context, experts warn that Paxlovid’s initial impact may be limited.

For more than a year, biotechnology-engineered antibody drugs have been the preferred treatment for COVID-19. But they are expensive, difficult to produce and require injections or infusions, usually in hospitals or clinics. In addition, laboratory tests have shown that the two main antibody drugs used in the United States are ineffective against omicron.

Pfizer’s pill has its own challenges.

Patients need to test positive for COVID-19 to get a prescription. And Paxlovid was only proven effective within five days of the onset of symptoms. Due to the shortage of testing supplies, experts worry that it may be unrealistic for patients to self-diagnose, receive testing, see a doctor, and prescribe within a narrow window.

Johns Hopkins University virologist Andrew Pekos (Andrew Pekosz) said: “If that time window is exceeded, I fully expect the effectiveness of this drug to decline.”

The FDA’s decision was based on the company’s 2,250 patients’ test results, which showed that taking the drug to patients with mild to moderate COVID-19 within three days of onset of symptoms can reduce hospitalizations and deaths by 89%. At the end of the 30-day study period, less than 1% of patients taking the drug were hospitalized and no one died, compared with 6.5% of the inpatients taking the fake drug group, of which 9 died.

Pfizer’s drug is part of a decades-old family of protease inhibitor antiviral drugs, which revolutionized the treatment of HIV and hepatitis C. These drugs block a key enzyme required for the virus to multiply in the human body.

The United States will pay approximately US$500 for each course of Pfizer treatment, including three pills taken twice a day for five days. Two of the pills are Paxlovid, and the third is a different antiviral drug that helps to increase the level of the main drug in the body.