Understanding How Vaccines Function

Vaccines serve as a crucial tool in training the immune system to recognize and respond to pathogens. When pathogens invade, lymphocytes—specific immune cells—generate antibodies to neutralize the antigens associated with the disease. The initial encounter with a pathogen can pose significant risks if the immune system is unprepared. Vaccines introduce safe antigens derived from the pathogens to educate lymphocytes, enabling them to produce targeted antibodies in advance. Two primary types of lymphocytes, B-cells and T-cells, play essential roles in this process. Helper T-cells stimulate B-cells to produce antibodies and aid in developing Killer T-cells, which directly attack infected cells.

Developing vaccines can be complex, as researchers strive to find secure methods for antigen introduction. Various types of vaccines have been developed, each with unique advantages and drawbacks, including:

• Live Attenuated Vaccines: These utilize weakened pathogens.
  • Advantages: Highly effective immune response, often requiring only one or two doses.
  • Disadvantages: Not suitable for individuals with compromised immune systems due to infection risk.
• Inactivated Vaccines: These involve killing the pathogen with heat or chemicals.
  • Advantages: No risk of causing disease.
  • Disadvantages: May require multiple doses for effective immunity.
• Subunit/Conjugate Vaccines: These inject specific proteins or carbohydrates from the pathogen.
  • Advantages: Minimal risk of infection.
  • Disadvantages: Isolation of specific components can be challenging.

Two experimental vaccine types are currently under investigation:

• DNA Vaccines: Aim to inject specific segments of the pathogen’s DNA.
  • Advantages: Not yet determined.
  • Disadvantages: Not yet determined.
• Recombinant Vector Vaccines: Similar to DNA vaccines but use a weakened pathogen as a vehicle.
  • Advantages: Not yet determined.
  • Disadvantages: Not yet determined.

Prospects for the Future

As we look at the current state of COVID-19 vaccine development, there are promising signs. Following the H1N1 pandemic, the first 100 million doses of a vaccine were available within eight months. However, the early response to COVID-19 faced challenges, such as faulty testing kits from the CDC that allowed the virus to spread undetected for weeks. Researchers have been tirelessly working on developing a COVID-19 vaccine, with 160 candidates currently in progress, aiming for a viable solution by the end of 2020.

The University of Oxford and AstraZeneca recently commenced Phase III trials for their vaccine candidate. This viral vector vaccine employs a modified adenovirus to introduce the coronavirus spike protein to the immune system, fostering an immune response. Given the diversity of populations affected by COVID-19, including those with weakened immune systems, the development of a universal vaccine that is safe for all is crucial. Viral vector vaccines pose a lower infection risk for immunocompromised individuals, making them a viable option.

As clinical trials progress, a breakthrough in the fight against COVID-19 appears imminent. In the meantime, maintaining social distancing and wearing masks remain the best strategies to curb virus transmission.

Citations

1. Schwartz, M. "The Life and Works of Louis Pasteur." Journal of Applied Microbiology, vol. 91, no. 4, 2001, pp. 597–601., doi:10.1046/j.1365–2672.2001.01495.x.