Almost all studies on vaccines and type 1 diabetes have found that vaccination does not increase the risk of type 1 diabetes or autoimmunity.
Researchers are also working to develop a vaccine to prevent or treat type 1 diabetes, e.g., the GAD65 vaccine (Ludvigsson 2017). The rotovirus vaccine may also be able to prevent type 1 diabetes, although the jury is still out.
My boys are fully vaccinated, including to COVID-19, and we all get flu shots every fall.
Vaccines and Type 1 Diabetes
Most studies have not found vaccines to be associated with the development of type 1 diabetes or type 1-associated autoantibodies. For example:
A meta-analysis of 11 studies found no associations between childhood type 1 diabetes and any routine vaccines (Morgan et al. 2016).
A large prospective study from Germany found that neither the type or quantity of vaccine was associated with the development of type 1 diabetes or associated autoantibodies (including including Bacille Calmette-Guerin vaccine; haemophilus influenzae vaccine; diphtheria, tetanus, and pertussis vaccine; tick-born encephalitis vaccine; or measles, mumps, and rubella vaccine) (Hummel et al. 2000). A more recent German study also found no association between vaccines and type 1 diabetes or autoimmunity (Beyerlein et al. 2017).
A Danish study did not find any associations between type 1 diabetes and vaccines, up to 2-4 years after vaccination (including hemophilus influenzae type B vaccine; diphtheria, tetanus, and inactivated poliovirus vaccine; diphtheria, tetanus, acellular pertussis, and inactivated poliovirus vaccine; whole-cell pertussis vaccine; measles, mumps, and rubella vaccine; and oral poliovirus vaccine (Hviid et al. 2004).
A U.S. study also found no associations between type 1 diabetes and any of the routinely recommended childhood vaccines (DeStefano et al. 2001).
A U.S. study found no associations between type 1 diabetes and the DTaP-IPV/Hib vaccine (Hansen et al. 2016).
In U.S. military personnel, no vaccines were associated with the development of type 1 diabetes (Duderstadt et al. 2012).
In Finland, the rotavirus vaccine had no effect on type 1 diabetes rates in Finnish children (Vaarala et al. 2017), and a placebo-controlled trial found no difference in type 1 diabetes incidence between those receiving this vaccine and those receiving a placebo after 12-14 years of follow-up (Hemming-Harlo et al 2019).
The live polio vaccine did not increase the risk of type 1-related autoimmunity as compared to the inactivated polio vaccine (Viskari et al. 2018).
On the other hand, a Swedish study found that the HiB (hemophilus influenza B) vaccine may induce type 1-related autoantibodies in 1 year old children (Wahlberg et al. 2003). Another study compared Finnish children who had received the HiB vaccine and those who had not (in the two years prior to the introduction of the vaccine). They found that children receiving 4 doses as compared to those receiving no doses had slightly higher rates of type 1 diabetes, beginning about 3-3.5 years after immunization. Yet HiB vaccination in the first month of life may also be associated with a decreased risk of type 1 diabetes (Classen and Classen 2002).
Does the Rotovirus Vaccine Prevent Type 1?
Vaccines may also be able to prevent type 1: in Australian infants and young children, after the oral rotavirus vaccine was added as a routine vaccines in 2007, type 1 diabetes incidence declined (Perrett et al. 2019a; note that there was an error in the original study so the overall numbers may not be right, but the findings still stand (Perrett et al. 2019b)). The change was only in children aged 4 and younger. In the U.S., there was a 33% decrease in type 1 diabetes incidence in children fully (not partially) vaccinated with the rotovirus vaccine compared to unvaccinated children. There was also a decrease in type 1 diabetes incidence in children aged 0-4 from 2006-2017, following the vaccine introduction in 2006 (Rogers et al. 2019). However, two large studies of U.S. children found no associations between partial or full rotovirus vaccination (Burke et al. 2020; Glanz et al. 2020). And as noted above, in Finland, there was no effect on type 1 diabetes rates (Vaarala et al. 2017). In Finland, however, the rotovirus vaccine was linked to a lower risk of celiac disease (Hemming-Harlo et al. 2019). In Israel, after the vaccine was used, there was a lower increasing prevalence of type 1 diabetes in children under 5 (Blumenfeld et al. 2021).
For some more discussion on this topic, see Harrison et al. 2019. I expect we will be seeing more follow up on this in other countries.
The BCG Vaccine: NOD Mice vs. Humans
The case of the bacillus Calmette-Guerin (BCG) vaccine is interesting, in that it shows how animal studies may not translate well to human studies. The BCG vaccine prevents the development of diabetes in NOD (non-obese diabetic) mice, an animal model of autoimmune diabetes (Harada et al. 1990). In humans, the BCG vaccine sometimes has been shown to preserve beta cell function when given just after diagnosis. On the basis of these studies, a prospective study in Germany examined whether vaccination might prevent beta cell damage in children genetically at risk for type 1 diabetes. The study compared children who received this vaccine before 3 months of age, after 3 months of age, and not at all. It found that the vaccine did not affect the development of type 1 diabetes-related autoantibodies. But, instead of being protective to beta cells, it actually sped up the rate of progression to type 1 in children who had these antibodies. And, the age of diabetes onset was significantly younger in children who had BCG vaccination (2.8 years) than in children who were not vaccinated (5 years). While this study does not suggest that BCG vaccination will increase the overall incidence of type 1 diabetes, it was found to accelerate development of the disease. The mechanism may involve stimulation of the immune system via inflammation (Huppmann et al. 2005). This is an interesting example of a case where something that can prevent diabetes in NOD mice accelerates type 1 diabetes in humans (see the Of Mice, Dogs, and Men page for more on this point). A large Canadian study found that the BCG vaccine in the first year of life did not affect the overall risk of childhood type 1 diabetes (Rousseau et al. 2016).
However, a recent reanalysis of Swedish data and analysis of Israeli data show that maybe the BCG vaccine was in fact protective against type 1 diabetes, in females anyhow (Klein 2020). And a study from Turkey and Greece found that one dose of the BCG vaccine at age 9 appeared to delay the onset of type 1 diabetes 2.5 years (Doupis et al. 2021).
The BCG vaccine is also being used by the Faustman lab to aim to reverse type 1 diabetes (Kühtreiber and Faustman 2019; Kühtreiber et al. 2018; Faustman 2020). This is a long story that others have addressed, so I won't go into it here. A review finds that "There is no robust evidence to support the use of the BCG vaccine for the treatment" of type 1 diabetes, "although the HbA1c levels tended to improve." (Chang et al. 2020).
The HPV vaccine Gardasil did not increase the risk of type 1 diabetes, or any of the other 15 autoimmune conditions analyzed (Chao et al. 2012). Additional reviews also found that the HPV vaccine did not increase the risk of type 1 diabetes or other autoimmune conditions (Grimaldi-Bensouda et al. 2017; Willame et al. 2019). A large, long-term California study found HPV did not increase the risk of type 1, even in the full 10 years following vaccination (Klein et al. 2019).
Vaccines and The Honeymoon Period
After type 1 diabetes diagnosis, many people have a "honeymoon period" of residual beta cell function that leads to better blood glucose control (also called "partial remission"). One study from Turkey found that children who were vaccinated for measles had a higher risk of having a honeymoon period after diagnosis (Bektaş et al. 2020).
Diabetes and Response to Vaccines
Does having type 1 diabetes affect people's response to vaccines? Perhaps. A study from Italy found that the hepatitis B vaccine was less effective in children with type 1 diabetes, but that a booster shot did help increase its effectiveness (Silvestri et al. 2019).
Other things can also affect the response to vaccines, for example: environmental chemicals...
Vaccines and Environmental Chemicals
Note that the presence of environmental chemicals in the body may affect the efficacy of vaccines (e.g., Grandjean et al. 2017). Infants with higher levels of persistent organic pollutants in their bodies (PCBs and DDE) had lower levels of antibody response to the BCG vaccine (Jusko et al. 2016). Children exposed to mercury (as well as malnutrition) also have a lower antibody response to vaccines (Wyatt et al. 2019). Infants exposed to phthalates also have a different response to vaccines (Yang et al. 2019). Early life phthalate exposure also appears to lower antibody response to vaccines in children into the teenaged years (Wen et al. 2020).
Vaccines are one instance where the presence of potentially toxic chemicals are sometimes included by design, not by accident. The vaccine preservative thimerosal, for example, contains the heavy metal mercury. The effect of thimerosal on the immune system is largely unknown (Havarinasab et al. 2005). A few Swedish researchers have tried to elucidate these effects in animal studies. One study showed, for example, that thimerosal exposure in mice was associated with the development of autoantibodies, and accelerated disease, at doses similar to those in infant vaccines (Havarinasab and Hultman 2006). Another found that thimerosal treatment of genetically susceptible mice leads first to an immunosuppression stage, followed by a second phase of immunostimulation and autoimmunity (Havarinasab et al. 2005). Thimerosal was removed from most childhood vaccines in 2001 in the U.S., but sometimes remains in some as an adjuvant, such as some flu shots, although it is being removed from those as well.
Aluminum has also been used in vaccines as an adjuvant, but at such small levels that the amount of aluminum in the bodies of people who are vaccinated vs unvaccinated is the same. Studies have found no link between aluminum and autoimmunity either (Goullé and Grangeot-Keros, 2019), and numerous studies have found "minimal" adverse effects (Corkins et al. 2019).
A Swedish study found that the H1N1 flu (swine flu) vaccine may affect the development of type 1 diabetes in young children, although exactly how is a bit unclear. The levels of some autoantibodies associated with type 1 diabetes were higher during and after the vaccine was administered, but the proportion of young children with a certain genetic risk diagnosed with type 1 diabetes decreased after vaccination. The authors state, "it cannot be excluded that the vaccine affected clinical onset of type 1 diabetes" and that, "it can therefore not be excluded that the vaccination campaign may have delayed the clinical onset in young high-risk children but induced an earlier diagnosis in others" (Svensson et al. 2014).
A study of the H1N1 vaccine and autoimmune disease did not find a different between those given shots with adjuvant and without. Rates of type 1 and other autoimmune diseases were also not different than background rates would predict (Isai et al. 2012). Another study of the H1N1 vaccine also found no increased risk of type 1 diabetes (Bardage et al. 2011).
There was some debate about a Swedish study of the swine flu vaccine Pandemrix used in 2009-2010 (e.g., Andersson 2014; Persson 2015; Persson et al. 2017). A bunch of these letters have since been retracted, it seems. The original study found no increased risk of type 1 diabetes from this vaccine (Persson et al. 2014). A reanalysis that found different conclusion was retracted (Andersson 2017). As a follow-up, a large population-wide study from Norway with 4 years of follow up found no increased risk of Pandemrix and type 1 diabetes (Ruiz et al. 2018). An international study also found no increased risk of autoimmunity or type 1 diabetes-- in fact, in Finland, it found a decreased risk of autoimmunity and type 1 was associated with this vaccine (Elding Larsson et al. 2018).
Interestingly, the Pandemerix vaccine may have affected the efficacy of a diabetes-prevention intervention trial using the GAD-alum vaccine. It appears the GAD-alum vaccine was more effective in preserving beta cell function in people newly diagnosed with type 1 diabetes who did not have the Pandemerix vaccine (Tavira et al. 2017).
The flu vaccine during pregnancy is not associated with an increased risk of gestational diabetes, and may help protect mother and baby (Mohammed et al. 2020).