Immunogenicity of hepatitis A-inactivated vaccine administered to seronegative infants, and serological follow-up 12 months after second dose

Breastmilk hepatitis A virus RNA in nursing mothers with acute hepatitis A virus infection

Breastmilk specimens from three women with acute hepatitis A virus (HAV) infection were studied. Anti-HAV immunoglobulin M and immunoglobulin G antibodies were detected in serum and breastmilk specimens of the three women. The three women also had serum HAV RNA. However, HAV RNA was detected only in two of the three breastmilk specimens. It is interesting that none of the three infants contracted clinical HAV infection. Furthermore, mothers with HAV infection should not be encouraged to discontinue breastfeeding.

Minimum Infective Dose of the Major Human Respiratory and Enteric Viruses Transmitted Through Food and the Environment

Viruses are a significant cause of morbidity and mortality around the world. Determining the minimum dose of virus particles that can initiate infection, termed the minimum infective dose (MID), is important for the development of risk assessment models in the fields of food and water treatment and the implementation of appropriate infection control strategies in healthcare settings. Both respiratory and enteric viruses can be shed at high titers from infected individuals even when the infection is asymptomatic. Presence of pre-existing antibodies has been shown to affect the infectious dose and to be protective against reinfection for many, but not all viruses. Most respiratory viruses appear to be as infective in humans as in tissue culture. Doses of <1 TCID50 of influenza virus, rhinovirus, and adenovirus were reported to infect 50% of the tested population. Similarly, low doses of the enteric viruses, norovirus, rotavirus, echovirus, poliovirus, and hepatitis A virus, caused infection in at least some of the volunteers tested. A number of factors may influence viruses' infectivity in experimentally infected human volunteers. These include host and pathogen factors as well as the experimental methodology. As a result, the reported infective doses of human viruses have to be interpreted with caution.

Solid organ transplantation and response to vaccination

Although early vaccination is recommended in candidates for solid organ transplantation (SOT), consensual protocols do not yet exist. We applied an SOT vaccination protocol in the Hospital Clinic of Barcelona (Spain). Serology was performed before and after vaccination and compliance with the vaccination schedule was analysed during the period 2003-2004. Two hundred and thirty seven patients (72.9% male; mean age 56.31 years, range 19-72) were included. A total of 74.5% of subjects susceptible to hepatitis B virus infection responded to hepatitis B vaccination. Most patients were protected against hepatitis A, varicella, measles, rubella and mumps. The vaccine protocol was implemented satisfactorily and the administration of two courses of hepatitis B vaccine was shown to be effective.