Vaccination & COVID 19

There are vaccines that can prevent healthy people from getting certain cancers caused by viruses. Like vaccines for the chicken pox or the flu, these vaccines protect the body from these viruses. This type of vaccine will only work if a person gets the vaccine before they are infected with the virus.

There are 2 types of vaccines that prevent cancer approved by the U.S. Food and Drug Administration (FDA):

HPV vaccine. The vaccine protects against the human papillomavirus (HPV). If this virus stays in the body for a long time, it can cause some types of cancer. The FDA has approved HPV vaccines to prevent:

• Cervical, vaginal, and vulvar cancers
• Anal cancer
• Genital warts

HPV can also cause other cancers the FDA has not approved the vaccine for, such as oral cancer.

Hepatitis B vaccine. This vaccine protects against the hepatitis B virus (HBV). This virus can cause liver cancer.

Are there vaccines that treat cancer?

There are vaccines that treat existing cancer, called treatment vaccines or therapeutic vaccines. These vaccines are a type of cancer treatment called immunotherapy. They work to boost the body's immune system to fight cancer. Doctors give treatment vaccines to people who already have cancer. Different treatment vaccines work in different ways. They can:

• Keep the cancer from coming back
• Destroy any cancer cells still in the body after treatments end
• Stop a tumor from growing or spreading

How do cancer treatment vaccines work?

Antigens, found on the surface of cells, are substances the body thinks are harmful. The immune system attacks the antigens and, in most cases, gets rid of them. This leaves the immune system with a "memory" that helps it fight those antigens in the future.

Cancer treatment vaccines boost the immune system's ability to find and destroy antigens. Often, cancer cells have certain molecules called cancer-specific antigens on their surface that healthy cells do not have. When a vaccine gives these molecules to a person, the molecules act as antigens. They tell the immune system to find and destroy cancer cells that have these molecules on their surface.

Some cancer vaccines are personalized. This means they are made for just 1 person. This type of vaccine is produced from samples of the person's tumor that are removed during surgery. Other cancer vaccines are not personalized and target certain cancer antigens that are not specific to an individual person. Doctors give these vaccines to people whose tumors have those antigens on the surface of the tumor cells.

Most cancer vaccines are only offered through clinical trials, which are research studies that use volunteers. In 2010, the FDA approved sipuleucel-T (Provenge) for people with metastatic prostate cancer, which is prostate cancer that has spread. Sipuleucel-T is tailored to each person through a series of steps:

• White blood cells are removed from the person's blood. White blood cells help the body fight infection and disease.
• The white blood cells are altered in a laboratory to target prostate cancer cells.
• Next, the doctor puts the altered cells back into the person through a vein. This is similar to a blood transfusion. These modified cells teach the immune system to find and destroy prostate cancer cells.

Another vaccine uses a weakened bacteria called Bacillus Calmette-Guérin (BCG) that is injected into the body. This weakened bacteria activates the immune system to treat early-stage bladder cancer.

What are the challenges of using treatment vaccines?

Making treatment vaccines that work is a challenge because:

Cancer cells suppress the immune system. This is how cancer is able to begin and grow in the first place. Researchers are using adjuvants in vaccines to try to fix this problem. An adjuvant is a substance added to a vaccine to improve the body's immune response.

Cancer cells start from a person's own healthy cells. As a result, the cancer cells may not "look" harmful to the immune system. The immune system may ignore the cells instead of finding and fighting them.

Larger or more advanced tumors are hard to get rid of using only a vaccine. This is 1 reason why doctors often give a cancer vaccine along with other treatment.

People who are sick or older can have weak immune systems. Their bodies may not be able to produce a strong immune response after they receive a vaccine. That limits how well a vaccine works. Also, some cancer treatments may weaken a person's immune system. This limits how well the body can respond to a vaccine.

For these reasons, some researchers think cancer treatment vaccines may work better for smaller tumors or cancer in its early stages.