The development of vaccines during the COVID-19 pandemic involved various scientific tools, sparking public curiosity about their contents. Non-human primates, particularly monkeys, have been part of this process, leading to questions about their role. This article clarifies the use of non-human primates in creating COVID-19 vaccines and addresses concerns about the composition of the final vaccine doses.
The Role of Non-Human Primates in COVID-19 Research
To explore new diseases, scientists use animal models that closely resemble human biology. Non-human primates, like macaques, were used to understand SARS-CoV-2 due to their genetic and physiological similarities to humans, including comparable respiratory and immune systems. This allowed researchers to observe how the virus infects the body, how it replicates, and the course of the disease, which often mirrors the progression in humans.
This research provided information on how the virus affects the body, particularly the lungs, and how the immune system responds to infection. Studies on macaques helped researchers investigate the effectiveness of potential antiviral drugs and therapies before human trials. This preclinical phase is a standard part of medical research, allowing scientists to gather safety and efficacy data that aided the rapid development of treatments and vaccines.
Monkey Cell Lines in Vaccine Development
Monkeys also play a role in manufacturing certain vaccines through cell lines, which are populations of cells grown in a laboratory. A common example is the Vero cell line, used in vaccine production since it was derived from the kidney cells of an African green monkey in 1962.
These cells act as factories for producing the viruses or viral components needed for certain vaccines, such as inactivated or some viral vector types. Vero cells are useful because they are susceptible to many viruses and can produce them in large quantities. This method has a long history in manufacturing, having been used for decades to produce vaccines for diseases like polio and rabies.
The process involves introducing the virus to the Vero cells, where it replicates. After enough virus has been grown, it is harvested from the cells. This method provides a controlled and scalable way to produce vaccine components, and the use of established cell lines ensures manufacturing consistency and safety.
Genetic Material in Final Vaccine Products
A primary concern is whether genetic material, like DNA from monkey cell lines, is present in the final vaccine. Vaccine manufacturing involves a purification process to remove materials used during production, including the cells. This process isolates the active component of the vaccine, such as an inactivated virus or a viral protein, from the cellular machinery used to create it.
Despite purification, small, fragmented traces of cellular DNA can remain. Regulatory bodies like the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO) are aware of this possibility. They have established safety limits for the amount of this residual DNA based on decades of experience with biological products.
The amount of residual DNA in vaccines is far below these safety thresholds, with guidelines often limiting it to 10 nanograms per dose. Sensitive testing methods like quantitative PCR (qPCR) are used to ensure each vaccine batch complies with these standards. The presence of these minute, fragmented DNA traces does not pose a risk of altering human genes.
Distinguishing COVID-19 from Monkeypox
Confusion can arise from the association of monkeys with both COVID-19 research and the disease mpox. However, COVID-19 and mpox are caused by different viruses. COVID-19 is caused by SARS-CoV-2, a coronavirus, while mpox is caused by the mpox virus, a member of the orthopoxvirus family that also includes smallpox.
The viruses also have different modes of transmission. SARS-CoV-2 spreads primarily through respiratory droplets and can be transmitted by individuals without symptoms. In contrast, mpox spreads mainly through close, direct contact with an infected person’s rash, scabs, or body fluids, and a person is contagious after symptoms appear.
The symptoms are also distinct. While both can begin with flu-like symptoms, mpox is characterized by a rash that develops into blisters. COVID-19 is a respiratory illness with a wider range of symptoms. These differences in the causative viruses, transmission, and symptoms underscore that they are separate diseases.