Pneumococcal conjugate vaccine

Pneumococcal conjugate vaccine is a vaccine used to protect infants and young children against disease caused by the bacterium Streptococcus pneumoniae (pneumococcus). Prevnar is a seven-valent vaccine, meaning that it contains the cell membrane sugars of seven serotypes of pneumococcus, conjugated with Diphtheria proteins. It is manufactured by Wyeth as the brand name Prevnar. In the United States, vaccination with Prevnar is recommended for all children younger than 2 years, and for unvaccinated children between 24 and 59 months old who are at high risk for pneumococcal infections.

Production technique
Prevnar is produced from seven genetically engineered strains of streptococcus pneumoniae bacteria. The characteristic bacterial capsule sugars are linked to recombinant diphtheria toxin (Corynebacterium diphtheriae). The vaccine uses serotypes 4,6B,9V,14,18C,19F, and 23F in the 7-valent formula, and will be adding six more with the release of 13V.

Centers for Disease Control recommendation
In 2001, the Centers for Disease Control (CDC), upon advice from its Advisory Committee on Immunization Practices, recommended the vaccine be administered to every infant and young child in the US. The resulting demand outstripped production, creating shortages not resolved until 2004. All children, according to current US vaccination schedules, should receive four doses, at two, four, six, and again between twelve and fifteen months of age.

Efficacy
Prevnar is designed to stop seven of about ninety bacteria which cause invasive pneumococcal disease. Each year, IPD kills approximately one million children worldwide.

Since approval, Prevnar's efficacy in preventing invasive pneumococcal disease has been documented by a number of epidemiologic studies.

Evidence supporting addition to routine vaccination schedules
According to one study, doctor visits by those who were diagnosed as having chronic ear infections and who took Prevnar dropped about 20 percent, and there was a similar 20 percent reduction in the number of children who needed tube implants to fight the infections, and overall ear infections were reduced by 9 percent.

For US children under the age of two, the chance of being diagnosed with an invasive pneumococcal disease was determined to be about 0.15% per year, or about one case each year for every 670 young children. Pneumococcal meningitis in childhood has been 'associated with' a mortality rate of approximately 1 in 178,571 children. According to data from the product insert, after one dose of the vaccine 0.016% of the recipients (3 out of 18,906) were diagnosed with invasive pneumococcal disease; 0.14% of controls (27 out of 18,910 injected with a different vaccine) got invasive pneumococcal disease. Thus, it was determined Prevnar decreases by 88% a child's relative risk of getting invasive pneumococcal disease. The absolute risk reduction is approximately 0.124%, or 1 fewer diseases each year per 808 young children.

According to a press release from Wyeth, "...a major clinical trial conducted by Kaiser Permanente.suggested that the vaccine is effective against invasive pneumococcal disease caused by seven serotypes (strains) of the bacteria most prevalent among children in the U.S." According to the Harvard Medical School, the Kaiser study was supported by a grant from Wyeth.

According to the Wyeth-funded research, "The study showed that children in the vaccine group fared better than those in the comparison group in other ways. In the primary analysis of all acute otitis media episodes (i.e. earaches), children receiving the investigational 7-valent pnemococcal vaccine (i.e. Prevnar) had 7 percent fewer new episodes."

Clinical study
Prevnar was administered to nearly 20,000 children prior to licensure, and the side effects were evaluated. The study did not show an increase the rate of diabetes, respiratory problems, or weight loss. However, rashes were found to occur in about one percent of children, and vomiting in almost ten percent, but such side effect rates are not unusual for vaccinations. According to the manufacturer's insert, croup, pneumonia, asthma, bronchiolitis, and wheezing were associated with the administration of Prevnar.

Of the 17,066 subjects who received at least one dose of Prevnar, there were 162 visits to the emergency room and eight reported seizures within three days of vaccination. Twelve deaths occurred among Prevnar recipients, compared to 21 deaths that occurred in the 'control group'; however, both groups received experimental vaccines.

Vaccination in the Developing World
Pneumococcal disease is the leading vaccine-preventable killer of young children worldwide, according to the World Health Organization (WHO), killing over 800,000 and up to a million children a year. Ninety percent of these deaths occur in the developing world. Historically 15-20 years pass before a new vaccine reaches one quarter of the population of the developing world. Pneumococcal vaccines Accelerated Development and Introduction Plan (PneumoADIP) is a GAVI Alliance (GAVI) funded project to accelerate the introduction of pneumococcal vaccinations into the developing world through partnerships between countries, donors, academia, international organizations and industry. With action now, a projected 5.4 million child deaths can be prevented by 2030. In May 2007, 30 of the 72 GAVI countries expressed interest in introducing pneumococcal conjugate vaccine between 2008 and 2010. These countries are Benin, Burundi, Congo, Rep. of Cote d'Ivoire, Djibouti, DRC, Ethiopia, Ghana, Guyana, Honduras, Indonesia, Kenya, Madagascar, Malawi, Mali, Mongolia, Nicaragua, Pakistan, Rwanda, Sao Tome and Principe, Senegal, Solomon Islands, Sri Lanka, Sudan, The Gambia, Timor Leste, Togo, Uganda, Yemen, and Zambia.

Sales
Prevnar is among Wyeth's top revenue producers, with sales in 2005 of $1.5 billion, up 43 percent from 2004.Wyeth Annual report

Controversy
Controversy has arisen regarding pneumococcal vaccine advertisements aired by Wyeth in Poland and Saudi Arabia. A television commercial for Prevnar, showing a dying child and its mother, was banned in Poland by the main pharmaceutical inspector (GIF), Zofia Ulz, on April 3, 2007. According to Ulz, the ad was designed to provoke fear to attract customers. Wyeth responded by asserting the tactic was used to increase awareness of the potential danger represented by pneumococcal infections.

References and notes

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