COVID-19 has spread rapidly since the winter of 2019, and even today, the whole world is still shrouded in its haze. Simultaneously, rapid progress has also been made in the R&D of drugs and vaccines for COVID-19 in the biomedical industry. Vaccines, as the first line of defense against the pandemic, have acted as an important role. So far, 7 vaccines have been approved for marketing in China. The all-course vaccination rate of COVID-19 vaccines in China is above 87%.
However, COVID-19 vaccines have been developed by scientists in a short term and vaccinated on a large scale, but the SARS-CoV-2 is getting more virulent from the original strain to Delta strain, and to the popular Omicron strain recently.
In terms of mRNA vaccines, adenovirus vector vaccines or inactivated vaccines, the vaccine defense line built by human beings seems to be inadequate in the face of Omicron strain. Studies have proved that after three doses of Sinovac vaccines, compared with the neutralizing antibody against the original virus, the titer of that against Delta and Omicron mutants have decreased by 3.3 times and 16.5 times respectively. The effectiveness has decreased to 45.7% in 10 weeks after vaccinating three doses of Pfizer mRNA vaccine, which is greatly reduced compared with the original virus strain (the effective rate of the original strain is 90%).
Responding to the mutating SARS-CoV-2, vaccine companies are updating their own vaccines continuously. Whether there is a universal vaccine with wide protection to prevent all mutants of SARS-CoV-2?
Universal vaccines come as expected.
Prior to answering this question, we'd like to take a macro view of SARS-CoV-2. Coronaviruses can be divided into two subfamilies, including Letovirinae and ortho-coronavirus. The latter can be further divided into four genera: α, β, γ and δ. SARS virus (SARS-CoV) and novel coronavirus (SARS-CoV-2) are β genus of the aforesaid subfamily.
Different technical paths, including recombinant protein, DNA and mRNA, may be adopted to the universal coronavirus vaccine. At present, the most remarkable research progress of universal coronavirus vaccine is still in early clinical stages.
A paper published in Science in 2021 proved that researchers used a vaccine platform called mosaic nanoparticles to generate four different nanoparticle vaccines. One vaccine only presented RBD (receptor binding domain) of SARS-CoV-2, and the other three vaccines could present RBD of four or eight different coronaviruses.
After injecting these vaccines into mice, the researchers found that a wide range of neutralizing antibody immune responses could be activated. The activated neutralizing antibody can not only identify and neutralize SARS-CoV-2, but also recognize and neutralize RBD of coronavirus strain which is not present in the nano-vaccines.
VBI Vaccines has rolled out a vaccine under research that concurrently presents the spike proteins of SARS-CoV, MERS-CoV and SARS-CoV2 by using this technology platform. In the animal test, this pancoronavirus candidate vaccine, named as VBI-2901, can not only increase the titer of neutralizing antibodies against the original COVID-19 strains, Beta variants, Delta and Omicron strains by 2-5 times, but also stimulate the antibody responses against SARS-CoV and MERS-CoV. The produced antibodies also can recognize the HCoV-OC43 strains not presented in the vaccine that cause seasonal flu. At present, the company is still optimizing this candidate vaccine.
In China, taking Recbio as an example, its vaccine ReCOV is not targeted for Omicron, but it has the possibility of "broad spectrum" and has good cross-immunity and immune persistence for major pandemic strains, including Omicron, in accordance with the clinical data disclosed by the company. It can be accounted to the targets of RBD and NTD, which contain multiple conservative epitopes.
According to the researchers, it will not be as difficult as that against HIV or influenza to find a vaccine with broad protection against coronavirus.
It depends on long-acting neutralizing antibody to fight against COVID-19.
Vaccination can remarkably reduce the risk of severe illness and mortality, but there are still some special groups that cannot be vaccinated ...
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