The ongoing COVID-19 pandemic, as a result of the SARS-CoV-2 virus, since December 2019, is a major health problem and concern worldwide. The pandemic has impacted various fields, from the social to the development of health science and technology. The virus has been mutating and thus producing several new variants, rushing research in the field of molecular biology to develop rapidly to overcome the problems that occur. Vaccine clinical studies are developing promptly with the aim of obtaining vaccines that are effective in suppressing the spread of the virus; however, the development of viral mutations raises concerns about the decreasing effectiveness of the resulting vaccine, which also results in the need for more in-depth studies. There have been 330 vaccines developed, including 136 clinical developments and 194 pre-clinical developments. The SARS-CoV-2 variant continues to evolve today, and it poses a challenge in testing the effectiveness of existing vaccines. This is a narrative review describing the emergence of the COVID-19 pandemic, development of vaccine platforms, identification of concerning mutations and virus variants in various countries of the world, and real-world monitoring of post-vaccination effectiveness and surveillance.

AbstrakKepiting bakau (Scylla serrata) merupakan salah satu spesies kunci dalam ekosistem mangrove yang memegang peranan yang sangat penting. Hutan mangrove yang ada di Kelurahan Belawan Sicanang sudah banyak mengalami konversi lahan seperti tambak dan pemukiman. Kondisi ini menyebabkan terjadinya penurunan kualitas habitat dan penurunan populasi untuk sumberdaya kepiting bakau akibat terjadinya kerusakan daerah asuhan dan mencari makan biota ini. Penelitian ini bertujuan untuk mengetahui kondisi ekologi mangrove, untuk mengetahui kelimpahan kepiting bakau (Scylla serrata), untuk mengetahui pertumbuhan kepiting bakau (Scylla serrata) di Hutan Mangrove Kelurahan Belawan Sicanang Kecamatan Medan Belawan Provinsi Sumatera Utara. Penelitian berlangsung pada Mei  Juni 2016. Metode yang digunakan dalam penentuan lokasi adalah purposive sampling dan dibagi menjadi 3 stasiun berdasarkan aktivitas yang berbeda. Struktur populasi kepiting bakau (Scylla serrata) ditinjau dari kelimpahan kepiting bakau (Scylla serrata), hubungan lebar karapas dengan bobot tubuh, pola pertumbuhan, dan faktor kondisi. Kualitas habitat kepiting bakau (Scylla serrata) dilihat dari kualitas air, tekstur substrat, Corganik, dan pasang surut. Hasil menunjukkan bahwa kelimpahan kepiting bakau (Scylla serrata) 16300 -17000 ind/ha, dengan pola pertumbuhan allometrik negatif (b<3), faktor kondisi berkisar antara 0  1 yang tergolong ke dalam pipih atau tidak gemuk. Kualitas air dan substrat yang dikaji termasuk ke dalam kualitas air yang menunjang kehidupan kepiting bakau (Scylla serrata), tekstur substrat yaitu lempung berpasir dan lempung liat berpasir, serta C-organik < 1% tergolong sangat rendah, dimana tipe pasang surutnya adalah mixed prevailing semidiurnal. Kata kunci: kepiting bakau; struktur populasi; kualitas air dan tanah AbstractMangrove crab (Scylla serrata) is one of the keystone species in the mangrove ecosystem, which had a very important role. Mangrove forests existed in Village Belawan Sicanang have been many experienced land conversion as embankment and settlements. These conditions led to degradation in habitat quality and population decline for mangrove crab due to the occurrence of the damage to the nursery ground and the feeding ground. The research aimed to determine abundance mangrove crabs and to determine the growth of mangrove crab. The research took place in May  June 2016. The method used in the determination of the location is purposive sampling and divided into 3 stations based on different activities. The mangrove crab population structure in terms of the abundance of mangrove crab, carapace width relation with body weight, growth pattern, and factor condition. The quality habitat mangrove crab viewed the water quality, the substrate texture, C-organic, and tides. The results showed that the growth pattern was negative allometric (b < 3), factor condition ranges between 0  1 which classified into flat or not fat. The water quality and substrate were assessed included in the water quality that supported life mangrove...

Tidal lakes are unique lakes because of the fluctuations of the water in the lake are influenced by the sea tides. Therefore, Tidal lakes are also called brackish lakes or salty lakes. Thus, the organisms that live in the lake must be able to adapt to the dynamics of brackish water changes. Therefore, the study of the biodiversity of flora and fauna is interesting to study related to organisms that are able to live and adapt to dynamic environments. This research was carried out in Siombak Lake, Medan City, North Sumatra Province from June to July 2018. The data collected were organisms in the form of flora (mangroves and aquatic plants) and fauna (ictiofauna or nekton which were fish, shrimp, crab, and mollusca). The results of research in the Siombak Lake ecosystem found 7 species of mangroves, 5 species of coastal plants, and 2 species of aquatic plant. Fauna found were 14 species of fish, 7 species of gastropods, and 1 species of bivalve, 1 species of shrimp and 1 species of crab.

Abstract. The study was conducted to determine the condition of the habitat and the diversity of fish in the watershed tambra. The higher diversity index (H ') was recorded in the Bahorok River with a value of 4.5 followed by Berkail River (3.45) and Landak River with a value of 2.46. Keywords : Biodiversity, nekton, Tor fish, fresh water crustaceaAbstrak. Penelitian ini dilakukan untuk mengetahui kondisi habitat dan keragaman ikan di DAS Wampu. Pengukuran kondisi habitat dengan mengukur parameter suhu, kecerahan, kecepatan arus, kedalaman, DO, pH, jenis substrat, lebar dan lebar badan sungai. Jenis nekton ditangkap dengan alat backpack electrofishing units dimana arus listrik yang dihasilkan bersumber dari batere 15 volt dan 9 ampere. Kondisi habitat pada bagian hulu DAS Wampu yaitu bertipe substrat batu besar, kerikil, dan pasir dengan arus yang sedang -besar serta perairan yang jernih. Parameter fisika-kimia perairan di hulu DAS Wampu masih layak dan cocok untuk habitat ikan, kepiting dan udang. Selama penelitian nekton yang terkoleksi sebanyak 15 jenis ikan dan 1 jenis kepiting air tawar serta 1 jenis udang air tawar. Pada survei ini ditemukan dua jenis ikan Tor yakni T. soro, dan T. Tambra. Keanekaragaman (H') tertinggi terdapat pada Sungai Bahorok dengan nilai 4,5 diikuti Sungai Berkail dengan nilai 3,45, dan Sungai Landak dengan nilai 2,46. Kata kunci: Biodiversitas, nekton, ikan Tor, krustacea air PendahuluanSungai adalah perairan yang sangat dinamis, karena ada dimensi waktu yang berhubungan dengan arus dan berfluktuasi setiap saat (Gordon et al., 2004; Mihov dan Hristov, 2011). Lebih lanjut Muhtadi et al. (2014) menyebutkan sungai sebagai perairan yang terbuka, memiliki arus, terdapat perbedaan gradien lingkungan, serta masih dipengaruhi oleh daratan. Sungai merupakan habitat berbagai jenis organisme perairan termasuk, plankton, benthos maupun nekton (Odum, 1996;Gordon et al., 2004). Nekton merupakan organisme yang dapat berenang dan bergerak aktif, misalnya ikan dan udang, termasuk amfibi dan serangga air besar (Welch, 1954;Odum, 1996). Walaupun udang dan kepiting hidupnya umumya di dasar perairan, akan tetapi karena memiliki kemampuan melawan arus dan berenang bebas sehingga dapat dikategorikan sebagai nekton.Kondisi dan karakteristik habitat perairan termasuk kualitas air sangat berpengaruhi terhadap pola persebaran, keanekaragaman, kelimpahan ikan, udang dan kepiting (Simanjuntak, 2012a;

Desrita, Muhtadi A, Tamba IS, Ariyanti J, Sibagariang RD. 2018. Community structure of nekton in the upstream of WampuWatershed, North Sumatra, Indonesia. Biodiversitas 19: 1366-1374. River is a habitat for many aquatic organisms. Water quality is themain river characteristic that strongly influences distribution pattern, biodiversity, and abundance of aquatic organisms. Nekton isaquatic organism that swims and moves actively on their desire, for example, fish, shrimp, amphibian and also big aquatic insects. Thepurpose of this research was to know the habitat condition and biodiversity of nekton in the upstream of Wampu watershed. The habitatcondition was measured by examining the temperature, visibility, flow velocity, depth of waters, dissolved oxygen, pH, kind ofsubstrate, the width of the river, body width of river and rate of flow of the river. The type of nekton was determined by catching thenekton using a backpack of electrofishing unit with an electric flow of 12 Volt and 9 Ampere. The upstream habitat condition of Wampuwatershed was characterized by big stone, pebble, sandy type of substrate with moderate to strong current flow, and the clear aquatic.Physical and chemical parameters in upstream of Wampu watershed were still sustainable and appropriate as habitat for fish and shrimp.The result of this research showed a variety of nekton collected, comprised of 27 species of fish, five species of shrimp of inland water.Two species of fish from Tor genera, i.e., T. soro and T. tambroides were also found in this study. The highest diversity (H´) in thisresearch site was the Bahorok River (2.12), followed by Landak River (1.93) at the second, and the lowest was Berkail River with onlyabout 1.50 diversity index.