The currently marketed varicella vaccines are based on the Oka strain of VZV which originated from Japan. It has been modified through sequential propagation in different human and animal cell cultures. Various formulations of such live, attenuated vaccines have been tested extensively and are approved for use in Japan, the Republic of Korea, the United States and several countries in Europe. Some formulations are approved for use at 9 months of age and older. Following a single dose of the above-mentioned vaccines, seroconversion is seen in about 95% of healthy children. From a logistic as well as an epidemiological point of view, the optimal age for varicella vaccination is 12-24 months. In Japan and several other countries 1 dose of the vaccine is considered sufficient, regardless of age. In the United States, 2 doses, 4-8 weeks apart, are recommended for adolescents and adults, in whom 78% were found to have seroconverted after the first, and 99% after the second dose of the vaccine. Children below 13 years receive only 1 dose. Small studies, using formulations different to that currently licensed in the US, show that when the vaccine is administered within 3 days after exposure to VZV, a postexposure protective efficacy of at least 90% may be expected. Varicella in persons who have received the vaccine ("break-through varicella") is substantially less severe than the disease in unvaccinated individuals. Further studies are needed to clarify the postexposure efficacy of the currently licensed product, especially in outbreak situations.
10 mg/kg/dose PO 3 times per day (Max: 1,000 mg/day) may be beneficial for some patients with frequent recurrences. Reevaluate after 6 to 12 months of continuous therapy. No clinical studies of prophylactic therapy for herpes labialis have been performed in children. For HIV-infected patients, 20 mg/kg/dose PO twice daily (Max: 800 mg/dose) is recommended by clinical guidelines. After prolonged period (., 1 year) of prophylaxis, consider stopping prophylaxis and assess patient to determine if additional prophylaxis is required. Although level of immune reconstitution should be a consideration, specific CD4 thresholds have not been determined.
Dry eye (keratoconjunctivitis sicca) is a common condition caused by decreased tear production or poor tear quality. It is associated with increased age, female sex, medications (., anticholinergics), and some medical conditions. 29 Diagnosis is based on clinical presentation and diagnostic tests. Tear osmolarity is the best single diagnostic test for dry eye. 30 , 31 The overall accuracy of the diagnosis increases when tear osmolarity is combined with assessment of tear turnover rate and evaporation. Some patients with dry eye may have ocular discomfort without tear film abnormality on examination. In these patients, treatment for dry eye can be initiated based on signs and symptoms. If Sjögren syndrome is suspected, testing for autoantibodies should be performed.