COVID-19 vaccination program in Cambodia: Achievements and remaining challenges.

Since Cambodia has been recognized as one of the low- and middle-income countries with a successful COVID-19 vaccine program, its program approaches were reviewed based mainly on press articles and announcements from the Ministry of Health. From the beginning, the government's proactive approach to securing vaccines and its flexibility prior to WHO Emergency Use Listing (EUL) contributed greatly to the success of the program. Vaccines were provided by COVAX and other countries, but more than half of the vaccines secured were Chinese vaccines purchased with government funds. The rollout of the vaccine has also been flexible, moving from a strategy of prioritizing risk groups and essential workers to one of expanding the campaign from population centers to rural areas, as well as gradually expanding the target age group, eventually targeting the population age 3 and older. As a result of this high level of commitment by the government and its flexible response, Cambodia has achieved 95% primary series coverage of the entire population, including those not eligible for vaccination. Although the sixth booster is now being administered in Cambodia and vaccination every six months was recommended, several challenges might be anticipated in continuing this program, including the lack of clear global guidance on how to sustain and modify the COVID-19 immunization program and vaccine fatigue after COVID-19 outbreaks have been controlled. How these challenges are overcome and how the COVID-19 vaccine program remains need to be carefully observed into the future.

Dietary intake of high-dose biotin inhibits spermatogenesis in young rats.

To characterize a new function of the water-soluble vitamin, biotin, in reproduction and early growth in mammals, the effects of high dietary doses of biotin on early spermatogenesis were biochemically and histologically investigated in male rats. Weaned rats were fed a CE-2 (control) diet containing 0.00004% biotin, or a control diet supplemented with 0.01%, 0.1%, or 1.0% biotin. Pair-fed rats were fed a control diet that was equal in calories to the amount ingested by the 1.0% biotin group, because food intake was decreased in the 1.0% biotin group. Food intake and body weight gain were lower in the 1.0% biotin group than in the control group. The kidney, brain and testis weights were significantly lower in the 1.0% biotin group than in the pair-fed group after 6 weeks of feeding. The accumulation of biotin in the liver and testis increased in a dose-dependent manner. In the 1.0% biotin group, the number of mature sperm was markedly lower, that of sperm with morphologically abnormal heads, mainly consisting of round heads, had increased. In addition, the development of seminiferous tubules was inhibited, and few spermatogonia and no spermatocytes were histologically observed. These results demonstrated that the long-term intake of high-dose biotin inhibited spermatogenesis in young male rats.