Alternative to vaccination! New antibodies should protect against future corona variants

Vaccination is the first choice in the fight against corona. It protects people best against a serious course of the disease. Nevertheless, scientists are continuing to research alternatives. They could be used, for example, in people who cannot tolerate a vaccination or for whom it is not sufficiently effective.

New hope is being raised by SC27, a so-called monoclonal antibody that researchers recently discovered. Antibodies are proteins that our immune system uses to fight pathogens, such as coronaviruses. Monoclonal antibodies are produced by a specific cell line and attack a small building block on the surface of viruses or bacteria.

Successfully tested on twelve corona variants

Monoclonal antibodies are usually genetically modified antibodies. They are already used in cancer therapy. The monoclonal antibody SC27 was developed by scientists from the USA. The team published its findings in the journal “Cell Reports Medicine” and immediately applied for a patent for its research.

SC27 delivered promising initial results: The antibody was tested on twelve corona variants – including the original variant from 2020, other early variants, currently circulating mutations and those that currently only occur in bats and pangolins. It was able to successfully combat all twelve in laboratory tests. This makes the researchers confident that SC27 could also work against future corona mutations.

SC27 fights coronaviruses in two ways:

1. It blocks the ACE2 binding site that the coronavirus uses to enter and infect healthy human cells. This prevents the coronavirus from attacking the cells.
2. It also binds to a hidden spot on the underside of the coronavirus's spike protein, which has barely changed from variant to variant. This is crucial! Only if SC27 finds a place to dock with future coronavirus mutations will it be able to successfully combat them.

“This makes it broader and more effective than any other monoclonal antibody that has been described in the scientific literature to date,” says study leader Greg Ippolito. However, he adds: SC27 has yet to prove itself in clinical trials on humans. So far, the antibody has only been successful in the laboratory in petri dishes and in initial tests on mice.

Faster development than vaccines

The next step will be studies on certain species of monkeys to see how a complete immune system will respond to treatment with SC27, then clinical trials on humans. The requirements for these human trials are somewhat lower for antibody therapies than for a vaccine. Testing phases could also be completed somewhat more quickly. Nevertheless, it will still take some time before a corresponding drug is used in doctors' offices.

If SC27 reaches market maturity, it would not be the first monoclonal antibody in the fight against corona. In the past, the drugs tixagevimab and cilgavimab, for example, temporarily represented an alternative to the corona vaccination. However, both drugs failed due to new corona mutations against which they were no more effective.

“Other Covid-19 antibodies have become ineffective over the past few years as Sars-CoV-2 has evolved,” says Greg Ippolito. He expects more from the newly researched antibodies, “because SC27 targets and binds to multiple parts of the virus' spike protein, including sections that do not mutate as frequently.”

Target group: immunocompromised people

If SC27 proves successful in further studies, it could be used in the future, like tixagevimab and cilgavimab once were, for immunocompromised people who cannot receive suitable vaccines – for example after an organ transplant or during chemotherapy. Or for those who cannot tolerate a vaccination or refuse it for other reasons.

Monoclonal antibodies are administered once via a syringe, but are not considered classic vaccines. The difference to a vaccination is that antibodies are injected directly and the immune system does not have to produce these antibodies itself.