The COVID-19 pandemic, also known as the coronavirus pandemic, is a global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identified in an outbreak in the Chinese city of Wuhan in December 2019.
Annual vaccination can help to provide protection against influenza. Influenza viruses, particularly IAV, evolve quickly, so flu vaccines are updated regularly to match which influenza strains are in circulation. Vaccines provide protection against IAV subtypes H1N1 H3N2 and one or two IBV subtypes.
- Influenza viruses
- >290,000–650,000 deaths per year
An mRNA vaccine is a type of vaccine that uses a copy of a molecule called messenger RNA (mRNA) to produce an immune response. 
- Medical Uses
- Side Effects
- Mechanisms of Action
- Developing World
- External Sources
Hib conjugate vaccines have been shown to be effective against all manifestations of Hib disease, with a clinical efficacy among fully vaccinated children estimated to be between 95–100%. The vaccine has also been shown to be immunogenic in patients at high risk of invasive disease. Hib vaccine is not effective against non-type B Haemophilus influe...
Clinical trials and ongoing surveillance have shown Hib vaccine to be safe. In general, adverse reactions to the vaccine are mild. The most common reactions are mild fever, loss of appetite, transient redness, swelling, or pain at the site of injection, occurring in 5–30% of vaccine recipients. More severe reactions are extremely rare.[citation nee...
Haemophilus influenzae type bis a bacterium with a polysaccharide capsule; the main component of this capsule is polyribosyl ribitol phosphate (PRP). Anti-PRP antibodies have a protective effect against Hib infections. However, the antibody response to PRP was quite variable in young children, and diminished rapidly after administration. This problem was due to recognition of the PRP antigen by B cells, but not T cells. In other words, even though B cell recognition was taking place, T cell r...
PRP covalently linked to a protein carrier was found to elicit a greater immune response than the polysaccharide form of the vaccine. This is due to the protein carrier being highly immunogenic in nature. The conjugate formulations show responses which are consistent with T-cell recruitment (namely a much stronger immune response). A memory effect (priming of the immune system against future attack by Hib) is also observed after administration; indicative that memory B cell formation is also...
Introduction of Hib vaccine in developing countries lagged behind that in developed countries for several reasons. The expense of the vaccine was large in comparison to the standard EPI vaccines. Poor disease surveillance systems and inadequate hospital laboratories failed to detect the disease, leading many experts to believe that Hib did not exis...
The first Hib vaccine licensed was a unconjugated polysaccharide vaccine, called PRP. This vaccine was first marketed in the United States in 1985. Similar to other unconjugated polysaccharide vaccines, serum antibody responses to PPP vaccine were highly age-dependent. Children under 18 months of age did not produce a positive response for this vaccine. As a result, the age group with the highest incidence of Hib disease was unprotected, limiting the usefulness of the vaccine. Also, post-lice...
The shortcomings of the polysaccharide vaccine led to the production of the Hib polysaccharide-protein conjugate vaccine. In 1987, the first Hib conjugate vaccine, which used diphtheria toxoid as the carrier protein (PRP-D), was licensed in the U.S. and initially recommended for children ages 18 to 59 months of age. This vaccine was based on work done by American scientists John Robbins and Rachel Schneerson. Attaching Hib polysaccharide to a protein carrier greatly increased the ability of t...
Multiple combinations of Hib and other vaccines have been licensed in the United States, reducing the number of injections necessary to vaccinate a child. Hib vaccine combined with diphtheria-tetanus-pertussis–polio vaccines and hepatitis B vaccines are available in the United States. The World Health Organization (WHO) has certified several Hib vaccine combinations, including a pentavalentdiphtheria-pertussis-tetanus-hepatitis B-Hib, for use in developing countries. There is not yet sufficie..."Haemophilus Influenzae Type b (Hib) Vaccine Information Statement". U.S. Centers for Disease Control and Prevention (CDC). August 2021."Haemophilus B Conjugate Vaccine (Meningococcal Protein Conjugate)". U.S. Food and Drug Administration (FDA). 24 April 2019."Haemophilus b Conjugate Vaccine (Tetanus Toxoid Conjugate)". U.S. Food and Drug Administration (FDA). 24 April 2019."Hiberix". U.S. Food and Drug Administration (FDA). 3 October 2019.
Polio Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus.  Approximately 75% of cases are asymptomatic;  mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe symptoms develop such as headache, neck stiffness, and paresthesia.
- Fever, sore throat
- No treatment other than supportive care
Human papillomavirus infection ( HPV infection) is caused by a DNA virus from the Papillomaviridae family.  Many HPV infections cause no symptoms and 90% resolve spontaneously within two years.  In some cases, an HPV infection persists and results in either warts or precancerous lesions.  These lesions, depending on the site affected ...
Spanish flu The 1918–1920 flu pandemic,  also known as the Great Influenza epidemic or by the common misnomer Spanish flu, was an exceptionally deadly global influenza pandemic caused by the H1N1 influenza A virus.