CLINICAL MATTERS

The Covid-19 pandemic has clearly demonstrated the immense value of vaccination. While many people continue to believe that vaccination is something that is only for children, the life-saving properties of vaccines are of benefit to people of all ages. Special populations like the elderly and those with immunocompromising conditions get even more protection from proper immunization. 

There has been renewed interest in adult vaccination, especially after it performed so well in ending the emergency phase of the pandemic. Historically and prior to the Covid-19 pandemic, doctors taking care of adults have not been very good at recommending vaccines. 

While nearly 100 percent of pediatricians recommend and give vaccines to their target population, less than 30 percent of internists and other adult medicine specialists did so before the pandemic. This is despite clear guidelines for adult vaccination for influenza, tetanus, pneumonia, shingles, and other vaccine-preventable diseases.

Many people see adult vaccination as an added and unnecessary cost. This, however, does not fully explain the lack of uptake for many of the Covid-19 boosters, which were given for free. Perhaps another reason for the hesitation to vaccinate is the fact that most vaccines continue to be delivered via an injection. No one likes getting stuck in the arm with a needle. 

In addition, most people who get a vaccine naturally feel a bit sick afterward and have some tenderness and discomfort in the site of injection. While intranasal vaccines have been developed for influenza, these are more expensive than the usual vaccine and seem to be less effective. Improving vaccine uptake among adults will need a multifactorial approach that addresses all these issues and more.

Two weeks ago, I admitted a patient in his 50s who had been bitten and scratched by a cat. Going by his history, he had gotten rabies immunoglobulin and a series of anti-rabies vaccines from the local clinic a few weeks before. There was, however, no record of tetanus toxoid vaccine administration. It was unclear whether this was missed or the patient voluntarily refused it, since this is part of the animal bite protocol. Unfortunately, he started developing prolonged muscle spasms and eventually had to be placed on the ventilator because of severe tetanus. 

These cases are thankfully very rare due to widespread vaccination. Tetanus has nearly been eradicated due to childhood vaccination. Protection against tetanus, however, begins to wane after 10 years from the last booster. This is why most countries recommend that adults get a tetanus toxoid vaccine every 10 years. In addition, a high-risk exposure such as an animal bite, a puncture wound, or a contaminated injury usually triggers giving a tetanus toxoid booster and the administration of tetanus immunoglobulin if the patient seeks proper and prompt medical attention. 

The alternative, like in my patient’s case, is catastrophic. The retail cost of a tetanus toxoid shot is under 100 pesos, and some government centers can provide it for free.

One vaccine that is universally recommended is the influenza vaccine. The main uncertainty with the flu vaccine is that the strain of influenza that is included in the current year’s vaccine is pretty much an educated guess. 

Since it takes a few months to produce the vaccine, health authorities need to decide ahead of time what strains are most likely going to circulate in the upcoming season. Some years they get it right, others they don’t and so vaccine effectiveness can vary from 30 percent to 70 percent. 

In recent years, tetravalent formulations (two influenza A strains and two influenza B strains) have been used to increase the possibility of a good match. Even with just partial protection from infection, there is usually enough of an immune response to protect against progression to severe diseases. This is where influenza vaccines excel, decreasing the risk of ICU admission for vaccinated elderly patients by over 70 percent.

Pneumonia vaccination is recommended for patients 50 years old and above and may be considered at younger ages for those with chronic lung disease and immunocompromising conditions. One frequent misconception is that pneumonia vaccination will prevent all pneumonias. Pneumonia vaccination is specific to Streptococcus pneumoniae, the bacteria responsible for about 60 to 70 percent of community-acquired pneumonia. There are other causes of pneumonia, including other bacteria, atypical organisms (Chlamydophyla, Mycoplasma and Legionella), viruses, and fungi. 

Streptococcus pneumoniae vaccination is important because it is by far the most common cause of pneumonia, and it can lead to severe complications, including bloodstream infection and brain infection (meningitis). There are many serotypes of Streptococcus pneumononiae and so the newest vaccines include more and more of them. There are two major types of pneumonia vaccine—conjugated vaccines and polysaccharide vaccines. The latest conjugated vaccines (PCV) induce more robust immune responses and protect against infection against anywhere from 13 to 21 of the most common serotypes. Polysaccharide vaccines (PPSV) are cheaper and typically protect against 21 serotypes but do not induce as strong an immune response. PPSV vaccines can protect against invasive pneumococcal disease but are not as protective against infection. In practice, the best and longest lasting protection is achieved by starting with a PCV vaccine followed by a PPSV vaccine after one year.

I wrote about the new shingles vaccine in a recent column (https://mb.com.ph/2023/9/5/have-shingles-don-t-mingle-until-you-get-vaccinated). This vaccine is indicated for 50 years old and above, as well as those with immunocompromising conditions.

These are just a few of the vaccines that can benefit adults. If there is uncertainty that an adult received his or her complete childhood vaccinations, catch-up vaccinations for MMR (measles, mumps, rubella), hepatitis A and B, HPV (human papilloma virus), and other vaccines can be offered. For adults who have lost their spleen (an immune organ in the abdomen which sometimes needs to be removed), additional vaccinations for Hib (Haemophilus influenzae type b), pneumonia, and meningitis are recommended. Recently, the US CDC has recommended that anyone six months old or older should receive the updated monovalent Covid-19 booster against XBB for additional protection. It is unclear when these vaccines will be available locally, but the most vulnerable populations should try to get them when they arrive.

Adult vaccination saves lives and it is important that we work with our doctors to maximize our protection. It has been said that aside from clean water and sanitation, there is no other public health intervention that has had such a wide impact as vaccination. In the Covid-19 pandemic alone, the first year of vaccination is estimated to have saved over 20 million lives. Undoubtedly, billions of people have been saved over the time period that vaccines have been available. Let’s continue that legacy. The next life that these vaccines save could be your own.