There are several ways to boost the immune system quickly, including:

1. Stay up-to-date on recommended vaccines: Vaccines are the best way to protect yourself from harmful illnesses.

2. Maintain a healthy diet: Eating a well-balanced diet that includes plenty of vegetables, fruits, legumes, whole grains, lean proteins, and healthy fats can help support a healthy immune system. Some specific nutrients that can boost the immune system include beta carotene, vitamin C, vitamin D, and zinc.

3. Exercise regularly: Physical activity can help reduce inflammation and support a healthy immune system.

4. Stay hydrated: Drinking plenty of water can help your body produce lymph, which carries white blood cells and other immune system cells.

5. Get enough sleep: Sleep is essential for a healthy immune system, and sleep loss can negatively affect different parts of the immune system.

6. Avoid smoking and excessive alcohol use: Smoking and excessive alcohol use can weaken the immune system and make the body less successful at fighting disease.

Its worth noting that no supplement or diet can protect you from COVID-19 specifically, and no supplement will cure or prevent disease.