We still don’t know.

Enter this important study published in Nature Medicine. Researchers from China studied 37 asymptomatic individuals in the Wanzhou District who were diagnosed with confirmed SARS-CoV-2 infections but had no relevant clinical symptoms in the preceding 14 days and during hospitalization.

They found that IgG levels and neutralizing antibodies — the antibodies that are much longer-lasting and are protective against further infection — started to decrease within 2–3 months after infection. 40% of patients with asymptomatic infection had no antibodies detected within 8 weeks of the initial infection. And, it seemed that those who had no symptoms had a weaker immune response to the virus.

On the one hand, this makes some sense. If you didn’t develop any symptoms, your immune response may not have been as robust as someone else who had a fever, chills, body aches, and other symptoms. Many of those symptoms are as a result of the immune response to the virus itself.

On the other hand, just because it seemed that those patients who had an asymptomatic infection with SARS-CoV-2 had decreased antibodies after 2–3 months, it does not mean that they will get the virus again and again and again. This is because of the nature of the adaptive immune response to infection.

When we first get an infection — any infection — we develop an initial immune response with antibodies called IgM. Then, later, the body develops IgG antibodies, which more protective and longer-lasting. When we take vaccines, we are coaxing the immune system to develop those IgG antibodies.

Some immune responses, like that to Measles or the Measles vaccine, are life-long. Others, like that to influenza, do not last our entire lives. We still don’t know exactly what kind of immune response is generated to SARS-CoV-2. Still, even if the initial immune response doesn’t last very long, the body usually keeps a memory of the previous infection. And so, if and when we get infected with SARS-CoV-2 again, the body’s immune system should remember the previous infection, and it should develop a very robust secondary immune response.

The key word is “should.” If the virus mutates, then all bets are off, as the body has not seen this new mutated version of the virus. Further, what this study does not answer — and it cannot answer unless researchers deliberately infect these individuals with SARS-CoV-2 — is if these individuals with asymptomatic infection become symptomatic if re-exposed to the same virus again.

Still, the implications of this research are significant.

If immunity doesn’t last very long, then having antibodies doesn’t mean we are free to disregard social distancing requirements. And, if a vaccine is developed, perhaps it may need to be taken every year — like the influenza vaccine — and not once in our lifetimes, like the measles vaccine.

In addition, if it is true that 40% of individuals who had asymptomatic infection don’t have detectable antibodies 8 weeks after infection, if they test negative for the antibodies, it does not mean that they never had Covid-19.

This will make it harder to determine the true extent of viral infection in the community.

As I have written before, this virus and the infection it causes is so new, there is so much that we don’t know. Every bit of information adds to the larger body of evidence.

True, there is so much out there that it is overwhelming at times. That said, it is still important to gather that information. This is because, the more we know, the better equipped we will be to fight this horrible scourge.

The post Antibodies to SARS-CoV-2 May Only Last 2–3 Months, Study Says appeared first on Medika Life.

Antigens are any substance that stimulates the immune system to produce antibodies. Antigens can be bacteria, viruses, or fungi that cause infection and disease. They can also be substances, called allergens, that bring on an allergic reaction. Common allergens include dust, pollen, animal dander, bee stings, or certain foods.

The Five Classes of Antibodies

There are five different kinds of antibodies, IgG, IgA, IgM, IgD, and IgE. Ig is the abbreviation for immunoglobulin, or antibody. Laboratories use Serological Testing to identify these antibodies in samples.

IgG antibodies are the most common and the most important. They circulate in the blood and other body fluids, defending against invading bacteria and viruses. The binding of IgG antibodies with bacterial or viral antigens activates other immune cells that engulf and destroy the antigens. The smallest of the antibodies, IgG moves easily across cell membranes. In humans, this mobility allows the IgG in a pregnant woman to pass through the placenta to her fetus, providing a temporary defense to her unborn child.

IgA antibodies are present in tears, saliva, and mucus, as well as in secretions of the respiratory, reproductive, digestive, and urinary tracts. IgA functions to neutralize bacteria and viruses and prevent them from entering the body or reaching the internal organs.

IgM is present in the blood and is the largest of the antibodies, combining five Y-shaped units. It functions similarly to IgG in defending against antigens but cannot cross membranes because of its size. IgM is the main antibody produced in an initial attack by a specific bacterial or viral antigen, while IgG is usually produced in later infections caused by the same agent.

IgD is present in small amounts in the blood. This class of antibodies is found mostly on the surface of B cells—cells that produce and release antibodies. IgD assists B cells in recognizing specific antigens.

IgE antibodies are present in tiny amounts in serum and are responsible for allergic reactions. IgE can bind to the surface of certain cells called mast cells, which contain strong chemicals, including histamine. When an allergen such as pollen binds with its specific IgE antibody, it stimulates the release of histamine from the mast cell. The irritating histamine causes the symptoms of an allergic reaction, such as runny nose, sneezing, and swollen tissues.

Can we produce antibodies in a laboratory?

Yes. Antibody production is carried out in the body by B cells. There are various methods for antibody production in the laboratory. Monoclonal antibodies can be produced through the use of hybridoma cells in vitro. Polyclonal antibodies are typically manufactured in rabbits.

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