It’s hard to believe, but the very first CDC pediatric vaccine schedule was only introduced in 1995.

Before the creation of the standardized CDC vaccine schedule, vaccination schedules varied depending on the individual healthcare provider and region. Some providers used their own schedules, while others followed guidelines put forth by professional organizations such as the American Academy of Pediatrics (AAP) and Advisory Committee on Immunization Practices (ACIP).

Prior to the 1990s and this more standardized schedule, there had been a trend of lower vaccine coverage that persisted for decades. In 1962, only 67% of children had received 3 doses of DPT vaccine by 2 years old. And even by 1973, only 59.5% of children had received 3 doses of polio vaccine by 2 years old.

Even well into the 1980s, the percentage of children vaccinated by 2 years of age was quite low by today’s standards–a little over 50% of children had taken 3 doses of polio vaccine, and a little over 60% of children received 3 doses of DPT vaccine by 2 years of age–and yet you would be hard pressed to find high mortality rates for infectious disease during these years.

• The above graph is from an MMWR here.
• Vaccine coverage levels – United States, 1962-2009 is here.

Vaccine coverage suddenly increased in the 1990s

What contributed to this sudden increase in vaccine coverage…of infants? There are many factors, and several key things that happened in the mid-1980s and early 1990s which paved the way for not only this sudden uptick in vaccine coverage of infants, but also opened the flood gates for many more vaccine products licensed and marketed for infants, after decades of literally no new vaccines:

• Between 1986 and 1990, Medicaid expanded to more pregnant women and children – Congress passed a series of laws to extend Medicaid coverage to additional pregnant women and children, based on participants’ family income relative to the Federal poverty level (FPL).
• 1986 – H.R.5546 – National Childhood Vaccine Injury Act of 1986 – ‘provides that no vaccine manufacturer shall be liable in a civil action for damages arising from a vaccine-related injury or death.’ After this, many new vaccines were introduced.
• 1991 – Switch to acellular DTaP vaccine – The acellular DTaP vaccine (diphtheria – tetanus – acellular pertussis) replaced the whole-cell DPT vaccine in 1991 for doses 4 and 5, and then doses 1-3 in 1996. This was significant because the DPT was associated with an uncomfortably high rate of adverse reactions, including seizures, tonic clonic convulsions, encephalopathy (brain swelling), and death, and was a major driver of vaccine hesitancy in the 1980s where you can see a big drop in vaccine uptake. (The DPT vaccine was connected to a cluster of SIDS deaths in Tennessee in 1978/1979 for example, and other countries had done away with the DPT, such as Japan) To learn more, read A Shot in the Dark by Barbara Loe Fisher.
• 1995 – first CDC standardized immunization schedule.
• 1997 – inactivated polio vaccine replaced oral polio vaccine – another problematic vaccine, the oral polio vaccine contained live polio virus and was known to cause poliomyelitis, including outbreaks since its first introduction in the early 1960s.

 

It’s interesting to note that this increase in vaccine coverage occurred simultaneously as the addition of many new vaccine products to the pediatric schedule:

1. Hepatitis B vaccine (1991 universal recommendation for infants)
2. Haemophilus influenzae type b (Hib) conjugate vaccine (1988)
3. Varicella (chickenpox) vaccine (1996)
4. Rotavirus vaccine (1998)
5. Hepatitis A vaccine (2000)
6. Meningococcal conjugate vaccine (2000)
7. 2nd dose of MMR (2001)
8. Pneumococcal conjugate vaccine (2001)
9. Influenza (2002)
10. Human papillomavirus (HPV) vaccine (2006)

For much of the history of vaccination, there was only one vaccine: the smallpox vaccine.

A few of the modern vaccines we have today were invented in the 1920s and 1930s, such as diphtheria, tetanus and pertussis, but were not widely used until the late 1940s and 1950s. In 1955, we saw the first polio vaccine introduced, and then the next vaccine would be measles in 1963, which was rolled into the MMR (measles – mumps – rubella vaccine) in 1971. That was literally it until the 1980s.

In 1962, an Act titled “Vaccination Assistance Act of 1962” was passed, which prioritized community vaccination programs against poliomyelitis, diphtheria, whooping cough and tetanus. This was the first government sponsored effort to get children immunized en masse, but coverage was still low.

Let’s stroll through the ages and see the various vaccine schedules, but know that the schedule does not mean 100% uptake or coverage. It was oftentimes much, much less.

1853 – Smallpox Vaccination

Prior to the 20th century, many countries had a smallpox vaccine mandate for infants. In England, The Vaccination Act of 1854 made smallpox vaccination compulsory for all infants by 3 months of age, unless the infant was sickly, and made defaulting parents liable to a fine or imprisonment.

In some States, there was a mandate for schoolchildren to show proof of smallpox vaccination and some health departments even went door to door.

In these early days, the smallpox vaccine wasn’t a vaccine the way we think of a vaccine today. There were no disposable syringes (the glass syringe wasn’t even invented yet), there were no refrigerators to store the vaccine liquid or ampuls.

Jenner’s contribution to science involved taking the pus, lymph and scab material of a cow pox lesion (sometimes other pox like diseases) from an animal (or a person), sometimes a cow, horse or sheep, and rubbing this “material” into a freshly cut scrape / open wound on the arm of an infant or child, made with a lancet. The scalpel like instrument was not sanitized of course, this was before modern ideas of sanitation and even germ theory. This process and “arm to arm” procedure would introduce all sorts of diseases into the new host, from syphilis, measles, tetanus, to hepatitis b and c, and herpes virus.

Jenner’s innovativeness rested in that his method used the cross-reactivity of cow pox virus (vaccinia) to cross-protect against smallpox virus (variola), resulting in a vaccination method (vacca is Latin for cow) that had fewer adverse events (less death and less severe reactions) than the reigning medical procedure, variolation, where instead of cow pox scabs, the medical procedure involved taking scabs and tissue and pus from smallpox victims and placing that into a child or person’s arm.

Variolation had a high mortality rate (around 3% but probably higher), and Jenner himself almost died from the procedure as a child. Interestingly, Jenner had noticed there were multiple strains of smallpox circulating in his time, which we have named variola major and variola minor, the second of which had a case fatality rate below 1% and fortunately became the dominant strain around 1900.

What vaccines were given in the 1900s?

It gets a little confusing here. There were antitoxins and immune globulins and serums, but none of these were technically vaccines, and they weren’t part of any routine medical care. During this time, there were injections for just about everything, but none of it was routine (and none of it was safe).

The smallpox vaccine continued to be given to infants and or children prior to school entry.

The diphtheria antitoxin was invented in 1890, but a vaccine for diphtheria toxoid came later, around the 1920s, and not widely used until the 1930s.

The first pertussis vaccine was developed in the 1920s by a French bacteriologist named Jules Bordet and his assistant Octave Gengou. They developed the vaccine by isolating the pertussis bacterium and then inactivating it with heat. The vaccine was first used in humans in 1933. But at this stage it was very experimental.

In 1933, Thorvald Madsen wrote a case report about two newborn infants who had been born healthy, and vaccinated shortly after their birth with a pertussis vaccine and who died shortly thereafter. He concluded that newborn infants are too young for this immunization, which is why it eventually was preferred at 6 weeks to 2 months of age.

1938 Immunization Schedule

During these years, vaccine schedules were buried in baby care brochures produced by the US Children’s Bureau, which was a precursor to the Administration for Children and Families (ACF), which is a division of the US Department of Health and Human Services (HHS).

Read the publication here.

1945 Vaccine Schedule

In 1946, assistant medical examiner Jacob Werne and his wife pathologist Irene Garrow published a case report detailing the delayed fatal anaphylactic shock of identical twins, aged 10 months, following the second injection of diphtheria toxoid and pertussis antigen vaccine. They both died the night and next morning after their vaccine.

1950s Vaccine Schedule

1953 Immunization Schedule

1956 Suggested Immunization Plan

In 1955, the first version of the polio vaccine came was introduced. It was the inactivate polio vaccine (IPV) by Jonas Salk. After a brief tragedy, dubbed The Cutter Incident, which resulted in a brief pause of the vaccine, the vaccine came back to market, and was largely marketed to school age children, who were seen as the most common victims of poliomyelitis.

To learn more about the interesting history of poliomyelitis, read Moth in the Iron Lung, by Forrest Maready.

From a Children’s Bureau brochure Your child from one to six, published in 1956.

1960s Immunization Schedule

In the early 1960s, Albert Sabin’s oral polio vaccine (OPV) popularly given on sugar cubes, replaced Jonas Salk’s IPV polio vaccine due to its inability to “control” polio outbreaks which had been happening in vaccinated populations in their usual cyclical fashion.

There was a key difference between the two vaccines, which is true of many vaccines. Sabin’s oral polio vaccine stimulated immunity in the intestines, where the polio virus replicates, and helped to reduce the spread of the infection. The Salk vaccine, on the other hand, only stimulated antibodies that circulated in the bloodstream, and did not prevent the virus from replicating in the intestines (and thus spreading to others). Poliovirus is a fecal-oral spread virus, so a vaccine delivered to the blood stream doesn’t interrupt this transmission.

Plus, there were many concerns about the safety of the Salk vaccine, which was produced using inactivated (killed) poliovirus that had a penchant for causing poliomyelitis. However, both vaccines would be able to cause poliomyelitis, and in the late 1990s, we would go back to the IPV as the vaccine of choice, even though it doesn’t stop transmission.

During these years, both vaccines also were inadvertently contaminated with various animal viruses that came from the monkey kidneys used to grow the poliovirus, such as SV-40, or simian virus #40, which government scientists like Bernice Eddy found were able to cause tumors and cancers in laboratory animals. She alerted her superior, who disregarded her warning.

For a few fascinating books on this topic, try reading Dr. Mary’s Monkey and The Virus and the Vaccine.

1963 Vaccine Schedule

The first measles vaccine was licensed for use in the United States in 1963, developed by Dr. Maurice Hilleman. It was a live attenuated vaccine, meaning it contained a weakened form of the virus. Shortly after, Dr. Hilleman developed the mumps vaccine, licensed for use in the United States in 1967, and then the rubella vaccine, also known as the German measles vaccine, was first licensed in the United States in 1969. They were combined into the MMR vaccine in 1971.

For several decades the MMR vaccine was only a one-dose series. The second dose would be adopted in 1989-1991, as more and more cases of measles were occurring in school aged children.

As the decades went by, more and more people became concerned about the risks associated with smallpox vaccination. Routine immunization against smallpox would end in 1972.

Here is a 1961 case report of a 3 month old baby girl who was vaccinated on the upper arm by a general practitioner using the ‘multiple pressure’ method. The baby was seen by a health visitor on the seventh day and appeared well; the vaccination showed a normal ‘take.’ The following morning she could not be wakened, and when the doctor arrived he found her dead, and her body was extremely hot to the touch with a rectal temperature of 108 degrees F.

The author writes:

It seems most probable that there was an acute overwhelming vaccinial infection with associated toxaemia leading to hyperpyrexia and death. This, however, does not entirely explain the asphyxia, which we can only account for by postulating spasm of the bronchioles, perhaps as an allergic reaction to large quantities of vaccinial antigen. The reaction appears to be an individual one; another child inoculated on the same day by the same practitioner with the same batch of vaccine behaved normally.

Here is another case report (1958) on four infants vaccinated against smallpox, who then developed generalized vaccinia (the infection spread from injection site) and one of which whose case was fatal.

Smallpox vaccination was often more adverse for people with history of eczema and other skin diseases. In 2008 researchers investigated a genetic basis for adverse reactions related to smallpox vaccination (as military still routinely get this vaccine) and found that MTHFR mutations are associated with a 2- to 4-fold risk depending on which mutation one has.

1966 Immunization Schedule

1970 Immunization Schedule

1980 Immunization Schedule

1983 Immunization Schedule

1989 Vaccine Schedule

1994 Vaccine Schedule

1995 Vaccine Schedule

The switch to inactivated polio vaccine (IPV) was due to ongoing cases of paralytic poliomyelitis associated with vaccine strain polio. Since 1961, an average of 9 cases of vaccine-associated paralytic poliomyelitis (VAPP) were confirmed each year from 1961 through 1989. 

2001 Immunization Schedule

2002 Vaccine Schedule

2005 Vaccine Schedule

2006 Vaccine Schedule

2008 Vaccine Schedule

2012 Immunization Schedule

2017 Immunization Schedule

2023 Immunization Schedule

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