Multiple studies published over the past few months highlight a pattern of decline in the IgG antibodies of recovered COVID-19 patients. This new research suggests patients infected with SARS-CoV-2—the virus that causes COVID-19—retain their IgG antibodies for only a few months after recovery, raising concerns about long-term immunity. 

IgM vs. IgG Antibodes

When a virus such as SARS-CoV-2 enters the body, the immune system begins to produce its first round of antibodies. These are known as IgM antibodies, and they are usually detectable three to six days after infection.¹ These antibodies serve as the body’s initial attempt at neutralizing the virus, but they fade rather quickly. As IgM antibodies dwindle, IgG antibodies start to develop and spike; they are typically detectable eight days after infection. IgG antibodies tend to provide long-term protection against reinfection.²

One of these studies, published on June 16, focused on two hospitals in Wuhan, China, the initial epicenter of COVID-19. Researchers analyzed IgG and IgM antibody levels in four groups of the population: 3,800 medical workers who were initially exposed to the virus, 20,000 members of the general population, 1,600 hospitalized patients (who were not hospitalized for COVID-19), and 1,500 patients with a confirmed case of COVID-19.³

Although 90% of COVID-19 patients tested positive for antibodies while the virus was still active in their body, only 4% of previously-exposed healthcare workers presented with these IgG antibodies. This finding led the researches to conclude that protective antibodies would not endure in the long-term after the SARS-CoV-2 virus is shed. 

“The most shocking part of our study, to me, is the extremely low viral levels in the blood serum of healthcare providers, most of whom had exposure to the virus in a highly-contagious environment without the appropriate personal protective equipment in the early days of the outbreak,” Fangijan Guo, MD, an assistant professor at the University of Texas Medical Branch and one of the authors of this study, tells Verywell. “The plausible explanation is that those healthcare providers did not produce long-lasting protective antibodies to SARS-CoV-2.”

Another study, published on July 21 by the David Geffen School of Medicine at the University of California, Los Angeles (UCLA), screened for antibodies in 30 confirmed COVID-19 patients and four suspected COVID-19 patients.⁴ Results built on the Wuhan study’s findings, suggesting that immunity is short-lived.

While UCLA researchers are still gathering data from COVID-19 patients, they believe IgG antibodies remain in the body for an average of 60 days.

The Implication for Recovered Patients

The fact that antibodies may not last long is nerve-wracking for people like Chiara DiGiallorenzo, 25, who is currently enrolled in the UCLA antibody study.

DiGiallorenzo, who is based in Los Angeles, is immunocompromised and tested positive for COVID-19 on March 6. She tells Verywell that this diagnosis was especially difficult for her because there were very few cases in California at the time, and local doctors were unfamiliar with testing and treatment protocols.

DiGiallorenzo publicly documented her experience with COVID-19 on her Instagram stories, sharing detailed snapshots of her struggles to encourage her followers to take the virus seriously. After her symptoms faded, she continued to test positive for a month and a half.

“It was a very frustrating and isolating experience,” DiGiallorenzo says. “The doctors were uncertain as to why this was happening—it was unclear if I was shedding the virus or if I was still infectious.” 

After finally getting a negative test result, she had an antibody screening in May. Results showed she had a "high antibody count." Her antibody levels will be retested during the UCLA study.

DiGiallorenzo says she fears reinfection, since the doctor she's been working with throughout the study is seeing a drop-off in antibodies among most participants.

"He has alerted us that most people are losing antibodies at an alarmingly fast rate in comparison to other coronaviruses," she says. "He had a patient lose them completely in three weeks."

What This Means For You ;

These studies show immunity is not guaranteed after you’ve been infected with SARS-CoV-2. Given that IgG antibodies shed in around three months, the chance of reinfection is possible. This research applies to both symptomatic and asymptomatic patients. 

What This Research Means for Herd Immunity ;

Herd immunity, which was initially proposed as a solution to COVID-19 in the UK, occurs when a significant portion of a population obtains immunity to a specific virus.⁵ This reduces the chances of person-to-person transmission, essentially wiping a virus off a map. Herd immunity can be achieved through vaccines or through actually acquiring—and recovering from—a virus. Either way, herd immunity relies on the effectiveness of neutralizing antibodies. 

What Is Herd Immunity?

Alexander Marchetti, a microbiology and immunology PhD candidate at the Indiana University School of Medicine, tells Verywell that if the discoveries about short-lived SARS-CoV-2 antibodies are further tested and confirmed, then herd immunity would prove futile.

Because there isn't a vaccine at this time, developing herd immunity to COVID-19 would involve a large number of people getting infected. Marchetti says this would come at the cost of an excessive amount of lives lost from COVID-19, given the pathogenicity of this disease.

According to Marchetti, earlier coronaviruses—such as SARS—had symptoms that manifested boldly and loudly in those afflicted, making it easier to separate the infected portion of the population from the non-infected portion. Additionally, SARS was only spread through symptomatic patients, while SARS-CoV-2 can be transmitted through asymptomatic people,⁶ increasing the chances of widespread infection. 

SARS killed about 10% of those infected, and the remaining part of the infected population was left with immunity.⁷ That doesn’t seem to be the case for this current strain of coronavirus, Marchetti says.

“What’s changed now is that this strain of coronavirus is less deadly than SARS, and that’s what’s allowing it to spread undetected," he says. "People can go for a week or two without symptoms and spread it. That has made it more virulent, yet less deadly on a mirco-scale. But in the macro-environment, if you zoom out, you get millions of people who are infected and hundreds of thousands more who are killed.”

SARS antibodies also tend to last for a much longer duration, according to Guo. 

“It is reported that even 210 days after symptom onset, neutralizing viral antibodies (anti-viral IgG) are still detectable in recovered SARS patients,” he says. “Why people infected with SARS-CoV-2 do not produce long-lasting protective antibodies is unknown. Further studies in this area are needed.” 

What This Research Means for Vaccines ;

The goal of a COVID-19 vaccine is to create an immune response against the SARS-CoV-2 virus. In other words, a vaccine should trigger antibody production. But because of the decrease in antibodies over time, scientists and doctors like Guo have their doubts about the efficiency of a potential vaccine. 

When Will We Have a COVID-19 Vaccine?

This finding would put a big question mark on the success of an effective vaccine against SARS-CoV-2.

— FANGIJAN GUO, MD

"This makes developing an effective vaccine more difficult, as long-lasting protective antibodies seem to be not produced,” Guo says. “What is worse, some reports demonstrate that people with severe COVID-19 have high antibody titers and people with mild diseases quickly lose their antibodies to SARS-CoV-2."

While research regarding antibodies continues, it’s important to maintain social distancing, wear masks, and properly isolate when infected. If you’re looking to test for antibodies, the Centers for Disease Control and Prevention (CDC) recommends you follow the testing and diagnosing protocols of your state, and reach out to your local healthcare providers and laboratories.⁸ 

What to Know About the COVID-19 Antibody Test

If you do choose to get an antibody test, it's important to remember what the test can and can't tell you.

"A positive COVID-19 antibody test will not provide people an immune passport to show that people are immune to SARS-CoV-2,” Guo says. “A positive test result only shows that they were infected or are still infected with SARS-CoV-2.”